Lewis Blood Group System: Antigens and Antibodies - Blood Bank

Chapter 8 **The Lewis system** The Lewis antigens are carbohydrate structures carried on glcolipids, and they are not produced by erythroid cells but absorbed from the plasma into the red cell membrane. The Le^a^ and Le^b^ are not product of alleles and they produce by Lewis gene *FUT3* is fucosyl...

Chapter 8 **The Lewis system** The Lewis antigens are carbohydrate structures carried on glcolipids, and they are not produced by erythroid cells but absorbed from the plasma into the red cell membrane. The Le^a^ and Le^b^ are not product of alleles and they produce by Lewis gene *FUT3* is fucosyltransferase encoded on chromosome 19 which produce α-4-L-fucosyltransferase. Figure 8-1 F 5 Figure 8-1 The Le^b^ appear by Le(*FUT3*) and Se(*FUT2*) where the *FUT3* gene produce α-4-L-fucosyltransferase and *FUT2* gene produce α-2-L-fucosyltransferase. The Lewis antigen found on platelets and lymphocytes but not on granulocytes or monocytes. The Lewis enzyme found in saliva, milk, sub maxillary glands gastric mucosa, kidney mucosa and cyst fluids. - There are four Lewis phenotypes 1. 2. 3. 4.  The Lewis substance present in secretions and antigens present on RBCs depending on *Lele*, *Sese* and *ABO genes* inherited. table 8-2 table8-2.jpg The Lewis genes affects the concentration of H, A, and B **type 1 chain** substance found in secretions but not affects the concentration of type 2 chain. The characteristic of Lewis and ABH substances found in secretions are illustrated in the following table 8-3  The Le^a^ and Le^b^ glycoproteins are present in the saliva of newborn infants but not in plasma at birth. Therefore cord blood and infants RBCs phenotype as Le(a-b-). The Lewis glycosphingolipids can be detectible after 10 days in the plasma where the baby if inherited Le and Se genes will become Le(a+b-) then to Le(a+b+) and finally to Le(a-b+) after 6-7 years but if the baby has Le and se will be remain as Le(a+b-). Low expression of Lewis antigens or transformation of Lewis positive to Lewis negative demonstrate on RBCs of pregnant women, patient with cancer, alcoholic cirrhosis and viral and parasitic infections due to abnormal lipid metabolism or genetic mutation where the one-third of Lewis antigen adsorbed to RBCs and remaining attach to lipoproteins and in these cases may increase of lipoproteins which decrease adsorbed of Lewis antigens on RBCs. **The Lewis antibodies** Lewis antibody present only in Le (a-b-) and are not considered clinically significant most not active at 37^o^C. The Lewis antibodies are naturally occurring and usually IgM which can binds complement and cause hemolysis in vivo and vitro. The Lewis antibodies react better with enzyme treated cells. - **Anti -- Le^a^** Anti -- Le^a^ is IgM and some time with IgG and can be detected at room temperature and AHG phase, and when reacts at 37^0^C may cause hemolytic transfusion reactions. The Le (a-b+) individual is not produce anti -- Le^a^. - **Anti - Le^b^** Anti -- Le^b^ is usually IgM and does not fix the complement like Anti -- Le^a^ and it usually produced from who has Le(a-b-) phenotype but some time produced from who has Le(a+b-) phenotype. The Anti -- Le**^b^** classified into categories anti -- Le^bH^ and anti -- Le^bL^. Anti -- Le^bH^ react to Le^b^ positive and H antigen positive. Anti -- Le^bL^ is the anti -- Le^b^ react to Le^b^ antigen positive regardless ABH antigens. Anti -- Le^bH^ and anti -- Le^bL^ are not implicated in hemolytic transfusion reactions. - **Anti -- Le^x^** Anti -- Le^x^ react to all Le(a+b-) and Le(a-b+) and 90% of cord blood Le(a-b-). Anti -- Le^x^ produced from Le(a-b-) individual. **Other Lewis Antigen** Le^c^ and Le^d^(Type 1 precursor and type 1 H structure) are found in Lewis negative individual Le(a-b-) with ABH non secretor and ABH secretor respectively. Le^x^(X) is type 2 isomer of Le^a^ which is formed by adding of Fucose-α(1-3)GlcNac linkage on the type 2 chain. Le^y^(Y) is type 2 isomer of Le^b^ which is formed by adding of Fucose-α(1-3)GlcNAc linkage on type 2 H substance. Figure (8-2) figure8-7.jpg Lewis antibodies are conceder insignificant in blood transfusion because : 1. Lewis antibodies can be neutralized by soluble lewis antigen in plasma. 2. The lewis antigens dissociate from RBCs as readily as they bind to the RBCs. 3. Lewis antibodies are IgM which can not cause HDN and lewis antigens are not fully developed at birth. A patient has Lewis antibodies is not required transfusion of Lewis negative antigen unless compatibility test is positive at AHG phase or no evidence of hemolysis in vitro. The Lewis antibodies can inhibited with saliva or with commercially Lewis substance when complicated antibody identification. **Biologic Significance of the Lewis System** The researcher found that the Lewis system is associated with factors causing certain diseases like peptic ulcers, ischemic heart disease, cancer and kidney transplant rejection. The Le^b^ is receptors for *Helicobacter pylori* which can cause chronic diseases due to expression antigen on *Helicobacter pylori.* **Important Points** - Lewis blood group antigens are not synthesized by the RBCs. These antigens are made by tissue cells, secreted into body fluids and plasma, and adsorbed onto the RBC membrane. - Lewis antigens present in secretions are glycoproteins; Lewis cell-bound antigens absorbed from plasma onto RBC membranes are glycolipids. - The Le gene codes for L-fucosyltransferase, which adds L-fucose to the type 1 chain. - Le gene is needed for the expression of Le^a^ substance, and Le and Se genes are needed to form Le^b^ substance. - Le^a^ antigen is formed by the addition of L-fucose to the number 4 carbon of N-acetylglucosamine of type 1 precursor structure. - All Le(a+b-) persons are ABH nonsecretors and have only Le^a^ substance in secretions. - Le^b^ antigen is formed when a second L-fucose is added to the number 4 carbon of the subterminal N-acetyl-D-glucosamine of type 1 H. - All Le(a-b+) persons are ABH secretors and have both Le^a^ and Le^b^ substances in secretions. - The most common Lewis phenotype in both whites and blacks is Le (a-b+). - The lele genotype is more common among blacks than in whites and will phenotype as Le (a-b-). - Lewis antigens are poorly expressed at birth. - Lewis antigens do not demonstrate dosage in serologic reactions. - Lewis antibodies are generally IgM (naturally occurring); antibodies are capable of binding complement and are enhanced by enzymes; Lewis substance in secretions can neutralize Lewis antibodies. - Lewis antibodies are frequently encountered in pregnant women. - Lewis antibodies are not considered significant in transfusion medicine Chapter 9 **Some Other Blood Group System** **The MNS Blood Group System (002)** **M (MNS1) and N (MNS2) ; Anti -- M and Anti -- N** MNS blood group system consisting of 45 antigen. The MN antigens are well developed at birth, and Anti -- M is common naturally occurring antibody. Most of Anti -- M and Anti -- N are not active at 37^o^C and are not clinically significant and they do not bind complement. Anti -- M react better with *MM* genotype than *MN* genotype and some time not react at all with *MN* genotype. Also Anti -- N react better with *NN* genotype than *MN* genotype and some time not react at all. Anti -- M and Anti -- N antibodies reactivity can be enhanced by increasing the serum or increasing the incubation time and decreasing temperature of incubation. Anti -- M and Anti -- N are clinical significant if they active at 37^o^C and can cause IHTRs and DHTRs. Anti -- M very rarely to cause HDFN. MN antigens are not present on WBCs or platelet. M and N are located at the N-terminus ( outer end ) of Glycophorin A (GPA), they are easily destroyed. The antigens are destroyed by enzymes ( ficin, papain, bromelin ), the ZZAP but not affected by DTT, AET, α-chymotrypsin, choroquine or glycine-acid-EDTA. M -- active GPA has serine at position 1 and glycine at position 5and N -- active GPA has leucine at position 1 and glutamic acid at position 5, Some people N antigen expressed on GPB and the most Anti -- N do not detect the N antigen on GPB The dialysis patient associated with formaldehyde may alter the M and N antigens and produce Anti - N^f^ which does not react at 37^o^C and is not clinically significant in transfusion. **S (MNS3) and s (MNS4) ; Anti -- S and Anti -- s** S and s represent a (Met29Thr) polymorphism in GPB. The S -- Methionine at 29 and s -- Threonine at 29. The S and s antigens are developed at birth. The S and s antigens are destroyed by Ficin, papain, bromelin, pronase and chymotrypsin but not destroyed by trypsin, DDT, AET, choroquine or glycine-acid-EDTA. Most of Anti -- S and Anti -- s are IgG and react at 37^o^C but some react at 10^o^ -- 22^o^C, if Anti -- S or Anti -- s suspected incubate at room temperature to help in identification. Anti -- S and Anti -- s can bind with complement and can cause severe HTRs and can cause severe and fatal HDFN. **S -- s -- U -- phenotype and Anti -- U** The U antigen is high frequency in the black African U (MNS5). The lack of *GYPB* response for S-, s-, U- phenotype, and there are two genes response for presence GPB. The U antigen is resistance to enzyme. Anti -- U is IgG and can cause severe and fatal HTRs and HDFN. **Other MNS antigen and antibodies** Mur antigen (MNS10) is rare and can cause severe HTRs and HDFN. The Low frequency antigen for MNS antigen resulting from gene conversion which contain and consisting of partly of *GYPA* gene and partly *GYPB* gene and lead to high frequency antigen. Anti -- Mi^a^ (MNS7) Miltenberger Series is low incidence antigen. GPA associates with protein band 3, which affects the expression of the antigen Wr^b^ the Diego blood group system. The GPB appears depend on the expression of Rh protein and Rh-associated glycoprotein which not express with Rh~null~ RBCs. The genes *GYPA* and *GYPB* which code for GPA and GPB respectively are located on chromosome 4 and they are codominant. The GPA, GFB and GPC are alternative receptors for *Plasmodium falciparum* to invasion the RBCs. **The P Blood Group System (003) and Globoside Blood Group System (028)** The P antigen is oligosaccharide antigen located on glycosphingolipids of the paragloboside series. The P system contain of P,P1and P^k^ but these antigens cannot be considered as a single blood group system therefore currently classified in ISBT nomenclature P1 is assigned to the P Blood Group System (003), P is assigned to the Globoside Blood Group System (028) and P^k^ and LKE are assigned to the Globoside Collection (209). The P1 gene located on chromosome 22 and the P gene located on chromosome 3. The P1, P2, p, P^k^~1~and P^k^~2~ phenotype describes on the following table Phenotype Antigens Present Possible Antibodies Antisera react ----------- ------------------ --------------------------- ------------------- P1 P1,P, P^k^ None Anti-P1, Anti-P P2 P, P^k^ Anti-P1 Anti-P p None Anti-PP1P^k^ (Anti-Tj^a^) P^k^~1~ P1,P^k^ Anti-P Anti-P1,Anti-P^k^ P^k^~2~ P^k^ Anti-P, Anti-P1 Anti-P^k^ The RBCs phenotypes as P1+ when using only Anti-P and react with and phenotypes as P1 -- when using only Anti-P and not react with. P1 antigen expression is after 12 weeks of gestation and will be fully expressed after 7 years. The Lutheran antigens inhibits the expression of P1 and may get negative serological test with anti-P. The P1 antigen deteriorates rapidly on storage. Anti-P1 is naturally occurring IgM and reacts at room temperature and 4^0^C. Anti-P1 is considered clinically insignificant when it reacts below 37^0^C. Anti-P1 which reacts at 37^0^C can cause immediate and delayed hemolytic reactions. Commotional P1 substance used for neutralize warm Anti-P Transfusion of P1 positive RBCs to P1 negative patient is acceptable if the cross match result is negative at 37^0^C and AHG phase which will not lead to a second response of the immune system. P Blood Group antigens are resistant to enzyme, DTT, chloroquine or glycine-acid-EDTA degradation. Biochemical synthesis for P Blood Group is illustrated below: **Anti -- PP~1~P^k^** is called anti -- Tj^a^, which produced from all p individual naturally occurring, this antibody reacts with all RBCs except p phenotype. Anti -- PP~1~P^k^ is IgM and IgG which can reacts at wide thermal range and can cause severe hemolytic transfusion reaction and HDFN, also it is associated with spontaneous abortions. **Anti -- P** is naturally occurring and produced from P^k^ individual and it is IgM and IgG which can react at wide thermal range and can cause severe hemolytic transfusion reaction and HDFN, and it is habitual with early abortion. Auto anti -- P associated with Paroxysmal Cold Hemoglobinuria and the IgG is responsible for cold reactive which characteristic as biphasic hemolysin, which sensitized the RBCs at cold temperature and it bonded to complement at 37^0^C. Anti -- P^k^ found in serum of p individual and isolated from anti -- PP~1~P^k^, auto anti -- P^k^ found in the serum of P~1~individual, Anti -- P^k^ activity inhibited with hydatid cyst fluid. **Luke antigens** have three phenotype Luke+, Luke(w) and Luke --. All individual with the p and P^k^ phenotype are Luke -. Anti-LKE react at 4°C. P1 and P^k^ have a receptor for *E. coli,* also *Streptococcus suis* adhere to P^k^ antigen. Globoside is the receptor of human parvovirus B19. **The I Blood Group System (027)** I system has only I antigen on oligosaccharides. The β 1,6 -- N -- acetylglucosaminyltransferase catalyses N -- acetylactosamin to form I antigen. The I and i antigens are part of ABOH oligosaccharide Type 2 chain. I and i antigens are found on leukocytes and platelets, the I antigen is also found on some animal RBCs like rabbit, sheep and cattle. The gene responsible for that enzyme (*GCNT2*). The i antigen is not converted antigen. Newborn and infant are I Negative but express i antigen strongly. I antigen reaches maximum strength at 6-18 months. Homozygous inactivity of (*GCNT2*) never converts i to I. Adult i phenotype produced alloanti -- I. Anti -- I exists both as a naturally occurring IgM or IgG antibody which reacts well at 4°C. Autoanti-I may be stimulated by microorganisms carrying I-like antigen such as *Mycoplasma pneumoniae* and *Listeria monocytogenes*. Cold autoanti -- I can interfere with indirect coomb\'s test which can be avoided using anti-IgG monoclonal, cold autoadsorption or pre-warm technique. Auto anti-I can blocking the I antigen and give negative serological test. Auto anti-I can cause Cold Haemagglutinin Disease (CHAD) and can cause hemolytic anemia. Anti-I does not cause HDFN. The i antigen is not part of I system because it is not controlled by *GCNT2* and it is not identified by alloantibody. Autoanti-i is IgM and react at 4°C. IgG form of anti-i may cause HDFN. Anti I system can be complexed with antibodies from other blood groups like anti-IA, anti-IB, anti-IAB, anti-IH, anti-iH, anti-IP~1~, anti-I^T^P~1~, anti-IHLe^b^, anti-iHLe^b^. **The I^T^ antigen** present on fetal RBCs at 11-16 weeks. Anti-I^T^ is complexed of IgM and IgG can react at 37°C and can cause warm autoimmune hemolytic anemia. **The Kell (006) and Kx (019) Blood Group System**  The Kell system now consists of 27 antigens numbered from KEL1 to KEL27. The Kell Glycoprotein and the *KEL* gene. The Kell antigens are located on red cell membrane glycoprotein type 2 C -- termini outside N -- termini in cytoplasm. Glycoprotein of Kell system is N -- glycosylated, and there is 5 to 6 sites. K antigen has 15 cysteine residues and is folded by disulphide bonding. The Kell antigen is consist of 731 amino acids. The Kell glycoprotein is covalently linked with Kx protein (440 amino acids) by a single disulphide bond. K system antigen is sensitive to disulphide bond reducing reagent like dithiothreitol (DDT) and 2-aminoethylisothiouronium bromide (AET). The KEL gene is located on chromosome 7. It is organized in to 19 exons of coding sequence. K (KEL1) has a frequency of about 9%. The k (KEL2) has a high frequency in population. Kp^a^ (KEL3) is found in about 2%. Kp ^b^ (KEL4) is high frequency in population. Kp^c^ (KEL21) has very low frequency in population. Js^a^ (KEL6) has variant frequency depend on population. Js^b^ (KEL7) is high frequency in population. UI^a^ and K23 are low frequency in absence of high frequency antigen K12, K13, K18, K19, K22, TOU, RAZ, KALT and KTIM. The Kell antigen is not found on platelets, lymphocytes, granulocytes or monocytes. The Kell antigen is present on fetal RBCs as early as 10 weeks (k, 7 weeks). The Kell antigens are not denatured by ficin and papain enzymes but are destroyed by trypsin and chymotrypsin when combined. Thiol reducing agents like DTT, 2-Mercaptoethanol, AET, glycine acid -- EDTA and ZZAP destroy Kell antigens but not Kx. **Kell antibodies** are considered clinically significant and may cause severe HDFN and severe HTRs (but less severe than Anti -- D). Kell system antibodies are usually IgG and predominantly IgG~1~. Anti-K usually cause extravascular hemolysis. Anti -- K (titer 8), causes suppression of erythropoiesis due to attack to erythroid precursor cells. The Kell glycoprotein appears on erythroid progenitors in a much early stage of erythropoiesis before they produce hemoglobin. Some anti -- K directly agglutinate K+ red cells. The IgM naturally occurring form of anti-K is associated with *E.coli* O125:B15 infection where this strain has K-like antigen, as well as mycobacteria, *Enterococcus faecalis*, *Morganella morganii, Campylobacter jejuni* and *Campylobacter coli* infections. Antibodies to Kp^a^, Js^a^ and other low incidence Kell antigens are not implicated with HDFN, anti-Kp^a^ is naturally occurring but most other are immune. Antibodies to k, Kp^b^, Js^b^ and other high incidence Kell antigens are rare but can mask other alloantibodies when present and complicates the identification. These antibodies can be denatured by using DTT or AET treated cells. **K~o~ phenotype.** Homozygosity for a variety of nonsense mutation, missense mutation and splice site mutation has been associated with K~o~ null phenotype, which none of the Kell system antigen is expressed. K~o~ produce Anti -- Ku (Anti -- KEL5) if immunized. Anti-Ku can cause HDFN and HTR. **Mcleod syndrome Mcleod Phenotype** **and K~x~ (XK1) Antigen**, Mcleod syndrome is associated with acanthocytosis and variety of muscular and neurological defect. Mcleod syndrome is very rare. Mcleod syndrome is X -- linked and found almost exclusively in boys. Mcleod syndrome results from homozygosity for inactivating mutation and deletion of the *XK* gene, causing absence of XK protein to expresses Kx antigen. Mcleod syndrome associated with weakly expression of Kell system and absent of Km (KEL20) and Kx. Chronic granulomatous disease (CGD) also related to deletion of X -- chromosome included *XK* gene. CGD patient with Mcleod syndrome usually produce Anti -- Kx and Anti -- Km. CGD and Mcleod syndrome should be avoid transfusion. There is unclear relationship between Kell antigens and Gerbich-negative phenotype Ge: -2,-3 and Ge: -2,-3,-4 where these Ge phenotype lead to weakness of Kell antigen (K~mod~), some K~mod~ produce resemble anti-Ku. **Acquired Kell antigen.** *Streptococcus faecium* may covert K -- cells to K+ cells. **The Duffy Blood Group System (008)** F 5 The antigens of Duffy system reside on glycoprotein of 336 amino acids encoded by Duffy gene (*DARC*). *DARC* consist of two exons, exon 1 encoding only the first seven amino acids of the Duffy glycoprotein. **Fy^a^ (FY1) and Fy^b^ (FY2)** Duffy system consists of two antigens with three allele Fy^a^, Fy^b^ and Fy which gives four phenotype.  Fy^a^ encoded Glu42, Fy^b^ encoded Asp42. *Fy/Fy* don't produce Duffy glycoprotein on red cell Fy (a-, b-). Fy is a result of mutation in the promoter region of the Duffy gene and this mutation prevents binding of erythroid specific GATA-1 transcription factor and prevents expression of the gene in erythroid tissue. Fy (a-b-) lack Duffy glycoprotein from their red cells but not from other tissue. Fy (a-b-) does not produce Anti -- Fy^b^ but rarely makes Anti -- Fy^3^. Fy^a^ and Fy^b^ antigen are sensitive to most proteolytic enzyme such as papain, ficin, bromelin, chymotrypsin and ZZAP but are not destroyed by trypsin, AET and glycine-acid EDTA. Fy^x^ is a weak form of Fy^b^. Duffy antigen is present in the fetal RBCs as early as 6 weeks. The antigens are not present in platelets, lymphocytes, monocytes and granulocytes but are present on other tissues like brain, colon, endothelium, lung, spleen, thyroid, thymus and kidney cells. **Anti -- Fy^a^ and Anti -- Fy^b^** are usually predominantly IgG~1~ and very rare naturally occurring. Some anti-Fy^a^ and anti-Fy^b^ does not react with heterozygous cells (Fy^(a+b+)^). They may cause IHTRs or DHTRs generally mild but some fatal. They can cause HDFN varying from mild to severe. They are generally detected by antiglobulin. **Fy^3^ and Fy^5^** *.* Fy (a-b-) is homozygous for inactivation mutation in Duffy gene they produce Anti -- Fy^3^. Fy^3^ is protease resistance. Fy^5^ is absent in Fy (a-b-) and also absent in Rh~null~ phenotype. Anti -- Fy^5^ has only been found in multiply transfused black people and can cause DHTRs. Anti -- Fy^3^ can cause IHTRs and DHTRs The Duffy glycoprotein called Duffy antigen receptor for chemokines (DARC) is receptor for interleukin-8 (IL -- 8) and melanoma growth stimulatory activity (MGSA). The Duffy glycoprotein is a receptor for *Plasmodium vivax* merozoites. Fy ^(a-b-)^ phenotype is resistant to invasion by *P. vivax* (70% Africans people are Fy (a-b-)) and *P. knowlesi* **The Kidd Blood Group System (009)** F 5 Jk^a^ and Jk^b^ is present in almost all population between 70% to 80%. *Jk^a^* and *Jk^b^* are inherited as codominant alleles on chromosome 18. Jk^a^ represents aspartic acid Asp280 in the Kidd glycoprotein. Jk^b^ represents asparagin Asn280 in the Kidd glycoprotein. Jk^a^ and Jk^b^ are present on the fetal RBCs as early as 11 and 7 weeks respectively. Kidd antigens are not very immunogenic and are not denatured by papain, ficin and are not affected by AET, DTT and glycine-acid EDTA. The Kidd antigen are not found on platelets, lymphocytes, monocytes and granulocytes. Anti -- Jk^a^ and Jk^b^ often bind complement and they are usually IgG or IgG plus IgM. Anti -- Kidd are complement dependent but only IgM binds to complement and not IgG. Kidd antibodies may cause severe IHTRs intravascular hemolysis and also is a very common cause of DHTRs. Anti -- Jk^a^ and Anti -- Jk^b^ very rarely cause severe HDFN. They are also associated with AIHA and may block antigen on RBCs and give a negative serological test with anti serum. Anti-Jk^a^ and anti-Jk^b^ react strongly with homozygous cells and give weak or negative results with heterozygous cells (Jk^(a+b+)^). Therefore to select blood for transfusion one should phenotype for both Jk^a^ and Jk^b^ antigens. Anti-Jk^a^ and anti-Jk^b^ may not be detectable with monospecific anti-IgG, therefore one should use polyspecific AHG. Fresh sample should be used since these antibodies are not detected in stored serum. The null phenotype Jk(a-b-) Jk -- 3 result from homozygosity for a silent gene at the *Jk* locus. Immunized Jk(a-b-) produce Anti -- Jk3, it is IgG and can cause IHTRs and DHTRs with mild HDFN. Anti-Jk3 is enhanced by enzyme. The inhibitor of Lutheran blood group *In(Lu)* inhibits the presence of Kidd antigens and gives serological result as Jk (a-b-) which does not produce anti Jk -- 3. The Kidd glycoprotein is a urea transporter. N -- and C -- terminal are cytoplasmic with one extracellular N -- glycosylation. Red cells have permits to urea (NH3) through Kidd glycoprotein and carrying urea away from the kidney. Jk (a-b-) cells are not lysed in 2M urea. **The Lutheran Blood Group System (005)** Lutheran is a glycoprotein complex system consisting of 19 antigens and *Lu gene* located on chromosome 19. Lu^a^/Lu^b^ (His77Arg); Lu^6^/Lu^9^ (Ser275Phe). The Lutheran glycoprotein consist of 597 amino acids. Most of the Lutheran antigens are very high incidence antigens while few are very low incidence antigens. The Lutheran antigen is present in the fetal RBCs as early as 10-12 weeks but is not fully developed. However, they become fully developed 15 years adult. Lutheran glycoprotein is not present on platelets, lymphocytes, monocytes or granulocytes but is present on other tissues like brain, lung, pancreas, placenta, skeletal muscles and hepatocytes. The monoclonal Anti-Lu^b^ (BRIC 108) is used to confirm negative results which can react with low expressions of Lu^b^. The Lutheran antigen is not affected by the enzymes ficin and papain but is destroyed by AET or DTT (Lu^b^ antigen), trypsin, chymotrypsin, pronase. **Lu (a-b-) null phenotype** results from one of 4 genetic disorders: Heterozygosity for In(Lu) independent regulator gene, Homozygosity for an inactive *LU* gene (Recessive *LuLu* type), Homozygosity for an X -- linked regulator gene, XS2 and Lu(w) phenotype. - **Dominant *In(Lu)* type** inheriting just one *In(Lu)* gene inhibits expression of all Lutheran antigens as well as P~1~, i, AnWj, Knops system antigen (Kn^a^ McC^a^, Sl^a^ and Yk^a^). The RBCs of *In(Lu)* have abnormal morphology due to storage at 4C which lead to hemolysis of RBCs. - **Recessive *LuLu* type** is a result of having a silent allele *LuLu* and not expressed in Lutheran antigens and produce anti-Lu^ab^ (anti-Lu3)**.** - **Recessive X-Linked inhibitor type** the inhibitor present on X-linked chromosome called *locus XS*, *XS1* the Lu^b^ antigen can be detected by adsorption-elution technique. The inhibitor leads to weak expression of Lutheran, P~1~ and i but not I blood group system. - **Lu(w) phenotype** the weak expression of antigens related to *In(Lu)* with a lesser degree of percent or allele to *In(Lu)* cause less suppression. **The Anti-Lu^a^** is IgM naturally occurring reacting at room temperature and some is IgG which react at 37C capable of binding complement. Most Lu^a^ antibodies are not clinically significant in transfusion, however, mild delayed transfusion reaction was reported. Anti-Lu^a^ may cause mild HDFN due to poor expression of antigen at birth. **The Anti-Lu^b^** is IgM naturally occurring reacting at room temperature but most anti-Lu^b^ is IgG and reactive at 37C. Anti-Lu^b^ may cause hemolytic transfusion reactions and mild HDFN. Lutheran antibodies are not considered clinically significant. Lu6/Lu9 and Lu8/Lu14 are high incidence antigens and the antibodies react with all RBCs except Lu(a-b-) cells. Lu4, Lu5, Lu7, Lu12, Lu13 and Lu20 are antigens of very high incidence that are absent from Lu(a-b-) RBCs. Summary of antibody characteristics shown in next table Summary of Antibody Characteristic -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ------------ -------- ------------------ ----------------- ------ ------ ------ --------------- Antibody Reactivity Enzyme Bind Com-plement Vitro Hemolysis HTR HDN ≤ RT 37 AHG M\*\* Most Few Few Destroy Rare No Few Mild-Severe N\*\* Most Few Few Destroy Rare No Rare Moderate S Some Some Most Variable effect Some No Yes Mild s Few Few Most Variable effect Few No Yes Mild-Severe U Rare Some Most No change Rare No Yes Mild-Severe P~1~\*\* Most Some Rare Enhance Rare Rare Rare No PP~1~P^k^† Most Some Some Enhance Most Most Yes Mild P† Most Some Some Enhance Most Some Yes Mild-Severe I° Most Few Few Enhance Most Few Rare No i° Most Few Few Enhance Most Few ? Mild K Some Some Most No change Some No Yes Mild-Severe k Few Few Most No change Some No Yes Mild Kp^a^ Some Some Most No change Some No Yes Mild Kp^b^ Few Few Most No change Some No Yes Mild Js^a^ Few Few Most No change Some No Yes Moderate Js^b^ No No Most No change Some No Yes Mild-Moderate Fy^a^ Rare Rare Most Destroy Some No Yes Mild-Severe Fy^b^ Rare Rare Most Destroy Some No Yes Yes Jk^a^ £ Few Few Most Enhance All Some Yes Mild Jk^b^£ Few Few Most Enhance All Some Yes Mild Lu^a^ Most Few Few Variable effect Some No ? Mild Lu^b^ Few Few Most Variable effect Some No Yes Mild \*\* Usually clinical insignificant ; †Potent hemolysin may be associated with early abortions; ° Usually autoantibodies clinically insignificant; £ Associated with severe delayed HTR, RT=room temperature **Important Points** **The MNS Blood Group System** - Anti-M and anti-N are cold-reactive saline agglutinins that do not bind complement or react with enzyme treated cells; anti-N has been found in renal patients undergoing dialysis treatment; both anti-M and anti-N may demonstrate dosage. - Anti-S and anti-s are IgG antibodies, reactive at 37^0^C and the antiglobulin phase; they may bind complement and have been associated with HDN and haemolytic transfusion reactions. - The S-s-U phenotype is found in blacks. - Anti-U is usually an IgG antibody and has been associated with haemolytic transfusion reactions and HDN. **The P Blood Group** - Anti-The P blood group consists of the biochemically related antigens P, P~1~, P^k^ and LKE; there is also a biochemical relationship between the P blood group antigens and the ABH and I antigens. - P~1~ antigen expression is variable; P~1~ antigen is poorly developed at birth. - Anti-P~1~ is a common naturally occurring IgM antibody in the sera of P~1~ -- individuals; it is usually a weak, cold-reactive saline agglutinin seldom detected in routine testing and can be neutralized with soluble P~1~ substance found in hydatid cyst fluid. - Anti-PP~1~P^k^ is produced by all p individuals early in life without RBC sensitization and reacts with all RBCs except those of other p individuals; antibodies may be a mixture of IgM and IgG, efficiently bind complement, and may demonstrate in-vitro haemolysis. - Anti-PP1Pk is produced by the rare p individuals early in life without RBC sensitization and reacts with all RBCs except those of other p individuals. Antibodies may be a mixture of IgM and IgG, efficiently bind complement, may demonstrate in vitro hemolysis, and can cause severe HTRs. Anti-PP1Pk is associated with spontaneous abortions. - Alloanti-P is found as a naturally occurring alloantibody in the sera of Pk individuals and is clinically significant. - Autoanti-P is most often the specificity associated with the cold-reactive IgG autoantibody in patients with paroxysmal cold hemoglobinuria (PCH). - The autoanti-P of PCH usually does not react by routine tests but is demonstrable as a biphasic hemolysin only in the Donath-Landsteiner test. **The I and i Antigens** - I and i antigens are not antithetical; they have a reciprocal relationship. - Most adult RBCs are rich in I and have only trace amounts of i antigen. - At birth, infant RBCs are rich in i; I is almost undetectable; over the next 18 months of development the infant's RBCs will convert from i to I antigen. - Anti-I is typically a benign, weak, naturally occurring saline-reactive IgM autoagglutinin, usually detectable only at 4^0^C. - Pathogenic anti-I is typically a strong cold autoagglutinin that demonstrates high titer reactivity at 40C and reacts over a wide thermal range (up to 30^0^-32^0^C). - Potent cold autoantibodies can mask clinically significant underlying alloantibodies and complicate pre-transfusion testing. - Patients with M. pneumoniae infections may develop strong cold agglutinins with autoanti-I specificity. - Anti-i is a rare IgM agglutinin that reacts optimally at 4^0^C; potent examples may be associated with infectious mononucleosis. **The Kell Blood Group System** - The Kell blood group antigens are well developed at birth and are not destroyed by enzymes. - The Kell blood group antigens are destroyed by DTT, ZZAP, and glycine-acid-EDTA. - Excluding ABO, the K antigen is rated second only to D antigen in immunogenicity. - The k antigen is a high-incidence antigen. - Anti-K is usually an IgG antibody reactive in the AHG phase and is made in response to pregnancy or transfusion of RBCs; it has been implicated in severe haemolytic transfusion reactions and HDN. - The McLeod phenotype, affecting only males, is described as a rare phenotype with decreased Kell system antigen expression. The McLeod syndrome includes the clinical manifestations of abnormal RBC morphology and compensated haemolytic anemia and neurologic and muscular abnormalities. Some males with the McLeod phenotype also have the X-linked chronic granulomatous disease. **The Duffy Blood Group System** - Fy^a^ and Fy~b~ antigens are destroyed by enzymes and ZZAP; they are well developed at birth. The Fy(a-b-) phenotype is prevalent in blacks but virtually nonexistent in whites. - Fy(a-b-) RBCs were shown to resist infection by the malaria organisms *P.knowlesi* and *P. vivax*. - Anti-Fy^a^ and anti-Fy^b^ are usually IgG antibodies and react optimally at the antiglobulin phase of testing; both antibodies have been implicated in delayed haemolytic transfusion reactions and HDN. **The Kidd Blood Group System** - Anti-Jk^a^ and anti-Jk^b^ may demonstrate dosage, are often weak, and are found in combination with other antibodies; both are typically IgG and reactive in the antiglobulin test. - Kidd system antibodies may bind complement and are made in response to foreign RBC exposure during pregnancy or transfusion. - Kidd system antibodies are a common cause of delayed haemolytic transfusion reactions. - Kidd system antibody reactivity is enhanced with enzymes, LISS, and PEG. **The Lutheran Blood Group System** - Lu^a^ and Lu^b^ are antigens produced by allelic codominant genes; they are poorly developed at birth. - Anti-Lu^a^ may be a naturally occurring saline agglutinin that reacts optimally at room temperature. - Anti-Lu^b^ is an IgG antibody reactive at the AHG phase; usually produced in response to foreign RBC exposure during pregnancy or transfusion. - The Lu(a--b--) phenotype is rare and may result from three different genetic backgrounds; only individuals with the recessive type Lu(a--b--) can make anti-Lu3. **Other Blood Groups and Antigens:** - The Diego system antigens are located on a major RBC protein, band 3, also known as the RBC anion exchanger (AE1). - Anti-Dia, anti-Dib, and anti-Wra are generally considered to be clinically significant; all have caused severe HTRs and HDFN. Anti-Wra is a relatively common antibody. - Wrb expression requires the presence of a normal GPA (MNS system); alloanti-Wrb is extremely rare. - Anti-Yta is a fairly common antibody to a high prevalence antigen that is sometimes clinically significant and sometimes insignificant. - The Xga antigen is found on the short arm of the X chromosome and is of higher prevalence in females (89%) than in males (66%). Although it is usually IgG, anti-Xga has not been implicated in HDFN or as a cause of HTRs. - Antibodies to Scianna system antigens are rare and little is known about their clinical significance. The rare null phenotype, Sc:--1,--2,--3, has been observed in the Marshall Islands and New Guinea. - In addition to the Doa and Dob antigens, the Gya, Hy, Joa antigens are assigned to the Dombrock system. Anti-Doa and anti-Dob have caused HTRs but no clinical HDFN; these antibodies are usually weak and difficult to identify. - The Colton system is composed of the antithetical Coa and Cob antigens as well as the high-prevalence Co3 antigen; the antigens are carried on aquaporin 1, a red cell water channel. The Colton antibodies have caused HTRs and HDFN. - LW has a phenotypic relationship with the D antigen; Rhnull RBCs type LW(a--b--). - Anti-LW reacts strongly with D+ RBCs and can look like anti-D. DTT treatment of test RBCs will distinguish between these two antibodies because the LW antigen is denatured by DTT, but the D antigen is not. In other words, anti-LW does not react with DTT treated D+ RBCs but anti-D does. - The antigens in the Chido/Rodgers system are located on the complement fragments C4B and C4A, respectively, that are adsorbed onto RBCs from plasma. - The clinically insignificant anti-Ch and anti-Rg react weakly, often to moderate or high-titer endpoints in the antiglobulin test and may be tentatively identified by plasma inhibition methods. - Gerbich-negative phenotypes are very rare outside of Papua, New Guinea. - Gerbich antibodies are sometimes clinically significant for transfusion and sometimes insignificant. Only three cases of serious HDFN due to anti-Ge3 have been reported. - The Cromer antigens are carried on the decay accelerating factor and are distributed in body fluids and on RBCs, WBCs, platelets, and placental tissue. - The rare anti-Cra and anti-Tca have been found only in black individuals; some examples have caused HTRs. - The Knops antigens are located on complement receptor 1 (CR1). Knops antibodies are clinically insignificant and have weak and "nebulous" reactivity at the antiglobulin phase; they are not inhibited by plasma. - The Ina antigen is more prevalent in Arab and Iranian populations, with Ina and Inb antigen expression being depressed on the dominant type Lu(a--b--) RBCs. - JMH antibodies most often occur in individuals with acquired JMH-- status. Anti-JMH in these individuals is not clinically significant. - Anti-Vel is most often IgG but can be IgM, and has caused severe immediate HTRs and HDFN. When serum is tested, anti-Vel characteristically causes in vitro hemolysis. - Anti-Ata has been found only in blacks; the antibody is usually IgG and has caused severe HTRs. - Anti-Jra is found more commonly in Japanese, but clinical significance is not well established, since it is a rare antibody; it has caused HTRs and a fatal case of HDFN. - Anti-Sda has characteristic shiny and refractile agglutinates under the microscope and is inhibited with urine from Sd(a+) individuals.