Blood Banking & Immunohematology PDF

# Blood Banking & Immunohematology ## Notice!! - This material can be printed for personal use only. - Sharing this material online or via email is prohibited. - Recording or downloading lectures is prohibited. ## All rights reserved. No part of this material may be reproduced, stored in a retrie...

# Blood Banking & Immunohematology ## Notice!! - This material can be printed for personal use only. - Sharing this material online or via email is prohibited. - Recording or downloading lectures is prohibited. ## All rights reserved. No part of this material may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, database, online or otherwise, without prior permission. ## Blood Banking & Immunohematology - 1 **Presented by:** Alyazeed Hussein, BSc **Outline:** - ABO & H blood group systems - Rh blood group system - Other blood group systems - Pretransfusion & compatibility testing - HDFN ## ABO & H Blood Group Systems ### Overview: Landsteiner's Rule, 1900-1901 - Landsteiner's Rule, 1900-1901 uses a table to show the relationship between ABO antigens and antibodies. It shows the plasma ABO antibodies and the red cell ABO antigens which are located on the red cells. The ABO phenotype can be identified by observing the presence or absence of A and B antigens. ### ABO & H Blood Group Systems - Most important blood group system - ABO Abs occur without exposure to RBCs (naturally occurring Abs!) - Anti-A and Anti-B are IgM Abs. - Anti-A and Anti-B antibodies found in the serum of group O individuals are composed primarily of the IgG class. - Abs detectable in infants at 3-6 months of age but not reach adult levels until 5 years of age. - ABO incompatibility can cause acute and immediate hemolysis of RBCs, leading to renal failure and death. - ABO locus is found on **chromosome 9 (H) on chromosome 19.** - Inheritance follows simple Mendelian genetics as one ABO gene from each parent. - A and B genes are dominant or codominant, and O is recessive. - The O gene is amorphic and produces no detectable Ag. - H gene h alleles are located on chromosome 19. - The H antigen is the precursor of A and B antigens - ABH genes code for produce specific glycosyltransferases enzyme that add specific sugars to a basic precursor substance called glycan (type 2 oligosaccharide chains on RBCs) that give rise to A, B, and H Ags. - The H gene must be inherited to form the ABO antigens on the RBCs, and the Se gene must be inherited to form the ABO antigens in secretions. - A, B, and H antigens, appropriate to the individual's ABO group, are found in saliva, urine, tears, bile, amniotic fluid, breast milk, exudate, and digestive fluids of secretors (Se). - Amount of H: O > A2> B > A2B > A1 > A1B. **Note that!!** 1. Immunodominant sugar for each Ag. 2. Least amount of H substance found in which blood group? ### Genotypes, Phenotypes & ABO Inheritance | Genotypes: actual genetic makeup| Phenotypes: physical expression of inherited traits | |---|---| | AA or AO | A| | BB or BO | B| | OO | O| | AB | AB| **Note that!!** 1. Genotype of group A individual? 2. Mother group O, father group A, child expression pattern? 3. Parents are A group, offspring blood group? 4. Percentage possibility of child for O farther, AB mother? 5. F is AB, M is B, the possibilities? 6. Genotype? 7. Phenotype? 8. AB parents, the possibilities? 9. F is OO, M is BB!? 10. F is A, M is O, baby blood group is O, the father pattern is? ### ABO Subgroups (A1 and A2) - 80% of group A individuals will be A1 and 20% will be A2. - Differentiate with anti-A1 lectin (Dolichos biflorus). - Some A2 individuals will demonstrate anti-A1 that is usually clinically insignificant. **Note that!!** 1. N-acetylgalactosamine is the immunodominant carbohydrate that react with? ## Bombay (`Oh`) Phenotype - First reported by Bhende in 1952 in Bombay (India). - hh genotype (H null). - No production of a-2-L-fucosyl-transferase (H-enzyme), no L-fucose, no A, B, O Ags produced. - No H antigens formed, therefore, no A or B antigens formed. - Anti-A, anti-B, anti-A,B, and anti-H present in the serum. - Phenotypes as blood group O. - RBCs will not react with anti-H lectin (Ulex Europaeus). - Can only be transfused with blood from another Bombay (`Oh`). **Note that!!** What is the antibodies that formed by O Bombay individual? ## ABO Discrepancy - The results of the red cell testing **do not agree with the results of expected serum testing.** - The most commonly encountered ABO discrepancies in the immunohematology laboratory are discrepancies relating to weak or missing ABO antibodies in serum/plasma testing. - Unexpected reaction: extra positive reaction or a weak or missing reaction in the forward and reverse grouping. - **Note that!!** the RBC and serum grouping reactions are very strong (3+ to 4+), weaker reactions usually represent the discrepancy. - If an ABO discrepancy is noted and transfusion is necessary before resolution!? ## ABO Discrepancy: Groups 1-4 - Groups one through four each have a different cause of discrepancy - These discrepancies are all identified by the red cell and/or serum grouping. | Group | Cause of Discrepancy | |---|---| | Group 1 | Affect reverse grouping. Newborns (until 3 to 6 months), elderly. Leukemic patients (CLL, malignant lymphoma). Immunosuppressive drugs. Congenital agammaglobulinemia, immunodeficiency diseases. BM transplantation, plasma exchange, ABO subgroups. **Most common** | | Group 2 | Affect forward grouping. A or B subgroups. Leukemia (weak A or B Ags), Hodgkin disease. Acquired B phenomenon (cancer of the colon). **The least common** | | Group 3 | Affect forward & reverse grouping. Due to protein or plasma abnormalities and rouleaux formation (MM), high fibrinogen. | | Group 4 | Affect forward & reverse grouping. Cold reactive autoantibodies, BM transplantation, alloantibodies. | ## ABO Discrepancies: Forward and Reverse Grouping **Forward** grouping looks for the antigens on the red cell (anti- A or anti-B with the patient red cells) **Reverse** grouping looks for the antibodies in the serum (the patient serum with known A1, B, or O cells) The following table shows different patterns of discrepancies, some causes, and resolution steps. The table is to be read as follows: * **Forward grouping** - Anti-A and Anti-B are added to the patient cells. If it is unknown, then 'O' is added as well in the same tube. * **Reverse grouping** - Patient serum is added to known cells: A1 cells, B cells, and O cells. | Forward Grouping | Reverse Grouping | Possible Cause | Resolution Steps | |---|---|---|---| | Anti-A 4+, anti-B 0 | A1 Cells 0, B Cells 0, O Cells 0, Autocontrol 0| Subgroup of A: probable A₂ with anti-A₁| Check age and diagnosis of patient and immunoglobulin levels; if possible incubate at RT for 30 min or at 4°C for 15 min; include group O and autologous cells at 4°C. React patient cells with anti-A₁ lectin, test serum against additional A1, A2, and O cells; run autocontrol. Wash RBCs; use saline dilution or saline replacement technique| | Anti-A 4+, anti-B 2+ | A1 Cells 2+, B Cells 2+, O Cells 2+| (1) Rouleaux (multiple myeloma patient; any patient with reversed albumin-to-globulin ratio or patients given plasma expanders) (2) Cold autoantibody (probable group AB with an auto anti-I)| (1) Perform cold panel and autoabsorb or rabbit erythrocyte stroma (REST) absorb (see Chapter 10), or reverse type at 37°C (2) Perform cold panel, autoabsorb or REST, and run panel on absorbed serum; select reverse cells lacking antigen for identified alloantibody; repeat reverse group on absorbed serum to determine true ABO group or at 37°C. Use anti-A₁ lectin, test serum against additional A1, A2, and O cells | | Anti-A 4+, anti-B 1+ | A1 Cells 1+, B Cells 1+, O Cells 0, Autocontrol 0 | Subgroup of AB; probable A₂B with anti-A₁| **Note that!!** What should be done if all forward and reverse ABO results are negative? **Interpretation of additional testing results:** | Patient serum | A1 Red Cells | B Red Cells | Autologous Red Cells | Conclusion | |---|---|---|---|---| | Pos | Pos | Pos | Neg | Group O | | Pos | Pos | Pos | Pos | Cold autoantibody | **Interpretation of Testing Results Screening Cells Autologous Red Cells Conclusion:** | Patient serum | Pos | Neg | Pos | Conclusion | |---|---|---|---|---| | Pos | Pos | Neg | | Cold alloantibody | | Pos | Pos | Pos | | Cold autoantibody | **Note that!!** 1. Reactions in front & back typing!! 2. What is the autocontrol? | Forward Grouping | Reverse Grouping | Possible Cause | Resolution Steps | |---|---|---|---| |Anti-A 0, anti-B 0 | A1 Cells 4+, B Cells Cells 4+, O Cells 0, Autocontrol 0 | O₁ Bombay |Test with anti-H lectin; test On cells if available; send to reference laboratory for confirmation or perform saliva studies or absorption/elution| | Anti-A 0, anti-B 4+ | A1 Cells 2+, B Cells 4+, O Cells 0, Autocontrol 0| Subgroup of A; probable A₂ with anti-A₁ | Check history of patient for lower gastrointestinal problem or septicemia; acidify anti-B typing reagent to pH 6.0 by adding 1 or 2 drops of 1 N HCl to 1 mL of anti-B antisera, and measure with a pH meter (this acidified anti-B antisera would agglutinate only true B antigens not acquired B antigens), test serum against autologous cells| |Anti-A 4+, anti-B 4+ | A1 Cells 0, B Cells 0, O Cells 0, Autocontrol 0| Subgroup of A with an acquired B antigen | Perform saliva studies or absorption/elution. Check history of patient for lower gastrointestinal problem or septicemia; acidify anti-B typing reagent to pH 6.0 by adding 1 or 2 drops of 1 N HCl to 1 mL of anti-B antisera, and measure with a pH meter (this acidified anti-B antisera would agglutinate only true B antigens not acquired B antigens), test serum against autologous cells | **Note that!!** Acquired B Ag seen in which blood group? - Acquired B Ag will not react at low pH. - Anti-B will not react with acquired B Ag. - RBCs treated with acetic anhydride for reacetylation of A Ag (N-acetylgalactosamine). ### ABO Testing: Front and Back Types * **Front type** is when anti-A, anti-B (reagents) are added to the patient red cells. * **Back type** is when the patient serum is added to known cells: A1 cells, B cells, (reagents) | **Front Type** | **Back Type** | |---|---| | Reagent: Anti-A - VS - Patient cells - MF 4+/0 | Reagent: Anti-B - VS - Patient cells - MF 4+/0 | | Reagent: A1 cells - VS - Patient serum - 0 | Reagent: B cells - VS - Patient serum - 0 | | **Interpretation: Front** type says the patient is both AB and O| **Interpretation: back** type says the patient is AB | **Note: Patient received 10 units of type O RBCs** ### Group B Patient Transfused with Group O RBCs **ABO Testing Results:** | Patient Red Cells with Reagent Red Cells | Patient Serum with Reagent Red Cells | |---|---| | Anti-A 0 | Anti-B 2+mf | | A1 4+ | B 0 | ## Rh Blood Group System - Rhesus monkey red cells. - Rh refers to a specific red blood cell (RBC) antigen (D). - Rh-specific antigens reside on proteins versus the carbohydrate antigens ABO and Hh. - The production of anti-D and other Rh blood group system antibodies requires immune red cell stimulation from red cells positive for the antigen. This exposure may occur during transfusion, transplantation or pregnancy, and usually react at AHG phase (IAT). - A primary cause of hemolytic disease of the fetus and newborn (HDFN, also called erythroblastosis fetalis). - **Five antigens make up the Rh system (D, C, c, E, e).** - Rh Genes: two closely linked genes located on chromosome 1 control expression of Rh proteins namely, RHD and RHCE. - RHD codes for RhD protein, RHCE codes for either RhCe, RhcE, Rhce, RhCE proteins. D neg (deletion of RHD gene). - **Inheritance:** codominant - **Immunogenicity:** ABO, Rh (D > c > E > C > e), Kell, Duffy, Kidd. - **Most antibodies are IgG** and bind at 37° C. ### Inheritance of the `D` Antigen | Genotype | Phenotype | |---|---| | DD, Dd | Rh positive | | dd | Rh negative | ### Fisher-Race: DCE Terminology - They postulated that the antigens of the system were produced by three closely linked sets of alleles. - Each gene was responsible for producing a product (or antigen) on the RBC surface. - D, d, C, c, and E, e, (d: absence of D Ag). - each person inherits a set of Rh genes from each parent (i.e., one D or d, one C or c, and one É or e). - Rh phenotype is reported as DCE rather than CDE. - C, c, E, and e recognized by specific antibodies. ### Weiner: Rh-Hr Terminology - One gene responsible for defining Rh. - R denotes the presence of the D antigen, while the r indicates the absence of D antigen. - Presence of C is indicated by a 1 or a single prime ('), while in c no 1 or ('). - Presence of E is indicated by 2 or double prime ("), while in e there no 2 or ("). - Presence of both C & E indicate by Rz or ry (DCE or dCE) respectively. - If the r precedes the h (i.e., rh' or rh"), this refers to the C or E antigens, respectively. - If the h precedes the r (i.e., hr’ or hr"), this refers to the c or e Ags, respectively. - Rh0 = D. ### Rh-Hr Terminology: Table | GENE | AGGLUTINOGEN | BLOOD FACTORS | SHORTHAND DESIGNATION | FISHER-RACE ANTIGENS | |---|---|---|---|---| | Rho | Rh0 | Rhohr'hr' | R0 | Dce | | Rhi | Rh1 | Rhohr'hr" | R1 | DCe | | Rh2 | Rh2 | Rhohr'rh" | R2 | DcE | | Rhz | Rhz | Rhohr'rh" | Rz | DCE | | rh | rh | hr'hr' | r | ce | | rh' | rh' | hr'hr" | r' | cE | | rh" | rh" | hr'rh" | r" | cE | | rhy | rhy | hr'rh" | ry | CE | ## Rosenfield and Coworkers: Alphanumeric Terminology - **Number to each antigen of the Rh system.** - A minus sign preceding a number designates the absence of the antigen. - Rh1= D, Rh2= C, Rh3= E, Rh4= c, and Rh5= e. - D+ C+ E + c negative, e negative = 1, 2, 3, -4, -5. - If e not tested Rh will be: 1, 2, 3, -4. **Common Rh Types (Three Nomenclatures):** | Common Genotypes | WIENER | FISHER-RACE | ROSENFIELD PHENOTYPE | |---|---|---|---| | R¹r | DCe/dce | Rh:1, 2, 3, 4, 5 | | R¹R¹ | DCe/DCe | Rh:1, 2, 3, 4, 5 | | rr | dce/dce | Rh: -1, -2, -3, 4, 5 | | R¹R² | DCe/DcE | Rh:1, 2, 3, 4, 5 | | R²r | DcE/dce | Rh:1, -2, 3, 4, 5 | | R²R² | DcE/DcE | Rh:1, 2, 3, 4, -5 | | r¹r | dCe/dce | Rh: -1, 2, 3, 4, 5 | | r¹r¹ | dCe/dCe | Rh: -1, 2, -3, -4, 5 | | r"r | dcE/dce | Rh: -1, -2, 3, 4, 5 | | r"r" | dcE/dcE | Rh: -1, -2, 3, 4, -5 | | Ror (RORO) | Dce/dce (Dce/Dce) | Rh:1, -2, -3, 4, 5 | | r'" (r'"r'" ) | dCe/dcE (dCE/dce) | Rh: -1, 2, 3, 4, 5 | **Rare Genotypes:** 1. **Heterozygous C?** 2. Write the FISHER-RACE antigens for individual with anti-c. 3. Pt with anti-E, need blood? 4. R²r to fisher-race? 5. R¹r to fisher-race? 6. R¹R² to fisher-race? 7. R2R2 to fisher-race? ### Inheritance of Rh Haplotypes - Because the genes coding for the Rh blood group system are very close on the chromosome, Rh antigens are inherited as haplotypes. This inheritance is illustrated in a pedigree chart and in a Punnett square. ### Complete Rh Typing **A complete Rh typing for antigens C, c, D, E, e, and e revealed negative results for C, D, and E. How is the individual designated?** - **D. Impossible to determine** ## Weak D Antigen (`Du`) - D antigen is weakly (reduced) expressed on the red cell. - Detection require the indirect antiglobulin test (IAT), negative at IS. - Donors must be tested for weak D. **Classification of weak D:** - **Weak D (Genetic reduced):** - RHD genes code for a weaker expression of the D antigen. - No anti-D. - **Weak D, C in trans (position effect):** - Decreased D Ag expression on RBC. - No anti-D. - **Weak D (Partial D) or D variant or D mosaic, qualitative:** - Some D-positive cells could be missing parts of the D antigen complex (epitopes). - Produce anti-D (whole D antigen). **Note:** Rh positive/weak D can receive Rh positive or Rh-negative blood. Rh negative can receive only Rh-negative blood. **Reaction With:** | Sample No. | Anti-D | Control | Interpretation | |---|---|---|---| | 1 | + | 0| D-positive| | 2| 0| 0| D- negative| | 3| +| +| Unable to interpret | **Note that!!** * D Ag that missed epitopes! ## Other (minor) Blood Group Systems ## System with Cold Antibodies ## Lewis (LE) - Lewis antigens: Lea & Leb antigens. - Soluble Ags produced by tissues, then adsorbed to RBCs surface (not synthesized by RBCs)!! - Not on cord cells. - Secreted into the body fluids (saliva and plasma). - **Most common phenotype is Le(a-b+)** - **Lewis antibodies:** - Anti-Lea, Anti-Leb - IgM, clinically insignificant. - Naturally occurring Abs. - Pregnant women transiently (a-b-) produce LE Abs. ### Interaction of ABO, H, Secretor & LE Genes | Genes | RBC phenotype | Antigens in secretions | Phenotype | Lewis Genotype | Secretor Genotype | |---|---|---|---|---|---| | Le, Se, A/B/H | A, B, H, Le(a-b+) | A, B, H, Lea, Leb | Le(a-b+) | Le | sese | | lele, Se, A/B/H | A, B, H, Le(a-b-) | A, B, H | Le(a-b-) | Le | Se | | Le, sese, A/B/H | A, B, H, Le(a+b) | Lea| Le(a+b) | Le | sese | | lele, sese, A/B/H | A, B, H, Le(a-b-) | None | Le(a-b-) | Le | sese | | Le, Se, th, A/B, H Para-Bombay (NB), Le(a-b+) | Le, Lea, Leb | Le, Lea, Le, A, B, H | Le(a-b+) | lele | sese or Se | **Anti-Lea is produced by:** - A.. Le(a-b-) - B. Le(a-b+). ## I Antigens - I antigens: - i positive in adult RBCs. - i positive in cord blood RBCs (newborn). - I antibodies: - Auto anti-I (IgM), common insignificant. - May associated with atypical pneumonia (mycoplasma) and CAD (agglutination). - Anti-i: less common, in patients with leukemia and people with CAD secondary to IM. ## P - P antigens: - P1 & P2. - P antibodies: - Anti-P1: IgM, clinically insignificant. - Auto-anti-P: IgG, Donath Landsteiner antibody. Paroxysmal cold hemoglobinuria (PCH). - Anti-P/anti-PP1Pk: recurrent abortions. ### Phenotypes, Antigens & Antibodies in the P1PK & GLOB Blood Group Systems | Phenotype | Antigens on RBCs | Antibodies in serum | |---|---|---| | P1 | P1, P, Pk (trace amount) | None| | P2 | P, Pk (trace amount) | None| | p | P1, Pk | Anti-P1 (25% will have) | | pk | Pk | Anti-P/anti-PP1Pk | | - | None | Anti-P & anti-PX2 | ## MNSs - Antigens: M, N, S, s, and U. - M+N+ is common (75% of population). **Characteristics of MNSs Antibodies:** | Antibody | Class | Clinical significance | Reactivity with enzyme-treated antigens | |---|---|---|---| | Anti-M | Ig M Class | No | No | | Anti-M | Ig G Class (rare) | Yes (HDFN) | No | | Anti-N | Ig M | No | No | | Anti-S | Ig G | Yes (DHTR,HDFN) | No | | Anti-s | Ig G | Yes (DHTR,HDFN) | No | | Anti-U | Ig G | Yes (DHTR,HDFN) | No | ### MNS System Phenotype Prevalence (%) by ethnicity | Phenotype | White | Black | |---|---|---| | M+N- | 30 | 25 | | M+N+ | 49 | 49 | | M-N+ | 21 | 26 | | S+s+ | 10 | 6 | | S+s- | 42 | 24 | | S-s+ | 48 | 68 | | S-s- | 0 | 2 | ## System with Warm Antibodies ## Kell System - Kell Ags: Jsa, Jsb, Kpa, Kpb. - K Ag (<9%). - k Ag (>90%). - K is more immunogenic after D Ag. - Inactivated with DTT. - Kell Abs: - Most common Anti-K (IgG), can cause HTR or HDN. - Anti-K (IgM) natural occurring in E. coli infection. ## Duffy System - Duffy Ags: Fya and Fyb - 68% of African American are Fy (a-b-/FyFy), provide natural immunity against P. vivax merozoites. - Fya more immunogenic, and Fyb - Duffy Abs: IgG, DHTR, HDN. PBF of asymptomatic man from Jazan shows ring stages of P. vivax!!! ## Kidd System - Kidd Ags: Jka and Jkb - Kidd Abs: - Anti-Jka and anti-Jkb, (IgG), HDN. - Associated with DHTR (most common). - Jk Null phenotype produce anti Jk3 antibody. ## Lutheran System - Antigens: - In 99.8% of people. - Lua and Lub - Most common Lu (a-b+). - Antibodies: IgGs - Anti-Luª: uncommon, not clinically significant, react at RT, rarely cause mild HDN. - Anti-Lub: Lu(a+b-), produced through exposure (transfusion or pregnancy), clinically significant (HTR and mild HDN). - Lu(a-b-): anti-Lu³. ## Antigens of High Incidence (High Frequency) - Ags that occur in at least 98% of the population. - Finding compatible units (antigen negative) for such patients is a major challenge. - **You know you have an antibody to high-frequency antigen when:** - All screen cell positive. - The auto-control is negative. - Reactions occur at AHG phase. - I, H, P, P1, Lub, Ch, Rg, Csa, Kna, McCa, SIa, JMH, Hro, K129, Wrb, Dib, Yta, Coa, Ch, Rg, Vel and Lan. **Which of the following has been associated with causing severe immediate HTRs?** - **C. Anti-Vel** ## Antigens of Low Incidence - The antibody screen is negative, and the crossmatch is positive. - Lua, Cw, Kpa, Wra, V, Bga, VS and Cob, Cx, Goa, Rh32, Mia, Mur, Dja, Swa, Ytb. ## Enzyme Treatment of Red Cell Antigens - Red cells proteolytic enzymes (bromelin, papain, ficin or trypsin). - This effect is reflected on the strength of the Ag-Ab reaction. - Used in antibody identification workups for confirmation of antibody specificity. **Effect of Enzyme-Treated Red Cells on Antibody Reactivity** | Enhanced antibody reaction | Decreased or destroyed antibody reaction | Unaffected antibody reaction | |---|---|---| | Lewis | Duffy | Kell| | P | M,N,S.Ss | Lutheran | | I | | | | Kidd | | | **Note:** Rh blood group system is enhanced by enzyme-treatment. **Note that!!** 1. Abs that enhance by enzyme treatment! 2. Abs that destroyed by enzyme treatment! ## Clinical Significance of Red Cell Antibodies | Clinically significant antibodies | Clinically insignificant antibodies | |---|---| | Kell | Lewis | | Kidd | I | | Duffy | P1 | | Lub | M | | S, s, U | N | | | Lutheran (Lu³) | **Note:** ABO and Rh antibodies are clinically significant. ## Disease-Associated Red Cell Antibodies or Antigens | Causative Ab or Ag | Disease | |---|---| | Anti-I | Chronic cold agglutinin disease | | Anti-i | Self-limited hemolysis after mycoplasma pneumonia | | Auto-anti -P (Donath Landsteiner antibody) | Hemolysis associated with infectious mononucleosis | | Duffy antigen | Paroxysmal cold hemoglobinuria | ## Blood Group Antibodies Related to Infections | Anti | Infection | |---|---| | Anti-M | Proteus mirabilis | | Anti-P₁ | Hydatidosis, liver flukes | | Anti-K | E. coli, Campylobacter jejuni, M. tuberculosis, E. faecalis | | Anti-Jkª | Micrococcus; Proteus Mirabilis | | Anti-P | E. Coli, measles, mumps, chickenpox, adenovirus, Cytomegalovirus, Epstein Barr Virus, syphilis, Haemophilus influenzae, M. pneumoniae | | Anti-Pr | Viral infections | | Anti-I | M. pneumoniae | | Anti-i | Epstein-Barr, Virus HIV | | Anti-Rx | Viral Infection | ## Human Leukocyte Antigens (HLAs) - **Genes of HLAs are part of major histocompatibility complex.** - Class-I on platelets, leukocytes and nucleated cells. - Class-II on APCs-phagocytic cells (B-lymphocytes, monocyte, macrophages, neutrophils, dendritic cell). - **Contributes to self and non-self recognition (organ and tissue transplantation, bone marrow and stem cell transplantation and platelet matching).** - **Incompatible HLAs causes:** - FNHTR. - TRALI. - GVHD posttransfusion. - Immune mediated PLT refractoriness (HLA-I). - HLA test applications - Paternity testing, forensic investigations. **Note that!!** 1. Which HLA is associated with Bechet disease? - HLA-B51. ## Platelet Antigens - Membranes have protein antigens. - Platelet antibodies occur less frequently in the general population because of less Ag variability. - Antibodies reacting with platelets may be ABO-HLA, or platelets specific. ### Diseases - Neonatal alloimmune thrombocytopenia (NAIT). - Posttransfusion purpura (PTP). - **Caused by Human platelet antigen (HPA-1a).** - **This sign appear 5-10 days of blood transfusion.** - **Treated with intravenous immunoglobulin (IVIG).** **مريضة نقلنالها بليتلت وحصلها نزول مفاجيء بالبليتلت ,وصار عندها كدمات بنفسجية ( Purpera ) المهم اش الحل ?** - pool platelet - washed platelet - radiated platelet - HLA copetipele platelet **HLA copetipele platelet** **✔** ## Pretransfusion & Compatibility Testing - ABO/Rh Ab screening/ID> crossmatching ## Antibody Screen - Screening cells are used in antibody detection tests. - Patients and donors may have performed antibodies to red cell antigens because of exposure to foreign red cell antigens from previous transfusions or pregnancies. - Group O donors are selected because the group O phenotype lacks A and B antigens, and so these red cells do not react with ABO antibodies present in patient or donor serum or plasma. - Use to detect unexpected antibodies (other than anti-A and anti-B). - Results: Any agglutination at any phase of testing indicates an atypical or unexpected antibody. - Add IgG-coated control cells (check cells) to all tubes with a negative reaction at AHG. Check cells must be agglutinated, or the test must be repeated. - Commercially available as two-vial or three-vial sets. - Capable of detecting most clinically significant red cell antibodies. Blood group antigens required on the screening cells include D, C, E, c, e, M, N, S, s, P1, Lea, Leb, K, k, Fya, Fyb, Jka, and Jkb. | Cell | D | C | E | c | e | f | CW | M | N | S | s | P1 | Lewis | Lutheran | Kell | Duffy | Kidd | |---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---| | I R1R1 (56) | + | + | + | 0 | 0 | + | 0 | + | + | + | 0 | + | + | + | + | + | + | + | | II R2R2 (89) | + | 0 | + | + | 0 | 0 | + | 0 | 0 | 0 | 0 | + | 0 | + | + | + | + | + | **The antigram is a profile of antigen phenotypes of each donor used in the screening cells. +, The antigen is present on the screening cell; 0, the antigen is absent on the screening cell.** ## Red Cell Dosage Phenomenon - Red cell from homozygous people possess more antigens per red cell than do cells from heterozygous people. - Antibody screen cells should be homozygous for the antigens that show dosage. - **The concept of dosage will be important when we are identifying red cell antibodies in antibody identification procedures.** - False negative result with heterozygous cells. - **Note D antigen does not cause dosage!!** - **Stronger agglutination when a red cell antigen is expressed from homozygous genes.** **Red Cell Antigen Dosage Phenomenon** | Antigens | Red cell antigens showing dosage | Red cell antigens not showing dosage | |---|---|---| | Rh (c, C, E, e) | | Lewis | | | Kidd | P | | | Duffy | | | "Double dose" Jk | "Single dose" Jk²/Jk | "Double dose" Jk| | MNS | | Kell | | | | Lu | **Dosage Effect** | Cell | D | C | E | c | e | f | CW | M | N | S | s | P1 | Lewis | Lutheran | Kell | Duffy | Kidd | Antibody reaction| |---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---| | 1 R1R1 | + | + | + | 0 | 0 | + | 0 | + | + | + | 0 | + | + | + | + | + | + | + | 3+ | | 2 R2R2 | + | 0 | + | + | 0 | 0 | + | 0 | 0 | 0 | 0 | + | 0 | + | + | + | + | + | 1+ | **Homozygous expressions of some red cell antigens react more strongly than heterozygous expressions. This antibody screen result shows that the antibody reacts more strongly (3+) with the red cell #1 homozygous (M+N-) expression than with the red cell #2 heterozygous (M+N+) expression of the antigen.** ## Which pair of cells would make the best screening cells? **A:** - Cell 1: Group A, D+C+c-E-e+, K+, Fy(a+b+), Jk(a+b+), M+N-S+s-