Lewis Blood Group System

Lewis Blood Group System

• There are two antigens: Le ᵃ and Le ᵇ.
• Development of the antigens shares a precursor substance with the ABO system, D-galactose –N acyle D- galactose amine-D galactose –D-gulcose ceramide.

leᵃ Antigen

• The Le gene acts on the precursor substance.
• L-fucose sugar is added in the sub-terminal end.

Le ᵇ Antigen

• The secretor gene and Le gene act together on the precursor substance.
• L-fucose sugar is added in both the terminal and sub-terminal ends.
• The Lewis blood group system requires the secretor gene of the ABO blood group system.

Phenotype and Genotype

• (le ᵃ +ve, Le ᵇ- ve) phenotype corresponds to the Le gene only.
• (le ᵃ +ve, Le ᵇ+ve) phenotype corresponds to the Le gene + secretory gene.
• (le ᵃ - ve, Le ᵇ- ve) phenotype corresponds to no Le gene.

Antibodies

• Anti-Le ᵃ and anti-Le ᵇ antibodies are present.
• They are IgM immune antibodies.
• Optimal reaction occurs at 15°C, but can react at more than 37°C.
• Fixes complement, leading to intravascular hemolysis and acute hemolytic transfusion reaction.
• It does not cross the placenta and therefore does not cause Hemolytic Disease of the Newborn (HDN).

Kell Blood Group System

• Cell antigens are second to D Ag in antigenicity. The order of antigenicity is (A,B,D,K,c,E,C,e).

Antigens

• One antigen (k) is controlled by two allelic genes: K gene (dominant) and k gene (silent).

Phenotype and Genotype

• K positive phenotype corresponds to KK or Kk genotype.
• K negative phenotype corresponds to kk genotype.

Other Antigens

• Other antigens in the same system are Kpᵃ, Kpᵇ, Kp ͨ, Jsᵃ, and Jsᵇ , but they are not very significant.
• Strict RBCs.
• Insoluble.
• Has different precursor substance.

Antibodies

• Anti-K is an IgG immune antibody resulting from immunization by previous transfusion.
• It is a warm antibody reacting at 37°C.
• Can cross the placenta, causing HDN.
• Cannot fix complement, causing extravascular hemolysis.

Duffy Blood Group System

Antigens

• Fyᵃ and Fy ᵇ antigens are controlled by Fyᵃ and Fy ᵇ genes.

Phenotype and Genotype

• (Fyᵃ+ve, Fy ᵇ-ve) phenotype corresponds to Fyᵃ Fyᵃ genotype.
• (Fyᵃ-ve, Fy ᵇ+ve) phenotype corresponds to Fyᵇ Fyᵇ genotype.
• (Fyᵃ+ve, Fy ᵇ+ve) phenotype corresponds to Fyᵃ Fyᵇ genotype.
• (Fyᵃ-ve, Fy ᵇ-ve) phenotype corresponds to no gene.

Criteria

• Duffy antigens are destroyed by enzymatic treatment of cells.
• Duffy antigens act as receptors for P. vivax, so (Fyᵃ-ve, Fyᵇ-ve) individuals are resistant to P. vivax infection.

Antibodies

• Anti-Fyᵃ and Anti-Fyᵇ are IgG immune antibodies.
• React optimally at 37°C.
• Cannot fix complement, causing extravascular hemolysis.
• Can cross the placenta, causing HDN.

Ii Blood Group System

Antigens

• I Ag and i Ag are the antigens.
• Before 2 months, individuals have i+ve Ag, and after 6 months, they have I+ve Ag.
• In between 2-6 months, a mixture of Ii Ags are present.
• Adult RBCs are I +ve, while cord RBCs are i+ve.

Antibodies

• Naturally occurring anti-I Ab are present despite the presence of I antigen, but they are in very low titer.
• They are IgM cold antibodies.
• Can fix complement, causing intravascular hemolysis.
• Cannot cross the placenta, so it does not cause HDN.

Kidd Blood Group System

Importance

• Can cause hemolytic disease, mainly HDN.

Antigens

• The antigens are Jkᵃ and Jkᵇ.

Phenotype and Genotype

• (JKᵃ+ve, JK ᵇ-ve ) phenotype corresponds to JKᵃ JK ᵃ genotype
• (JKᵃ-ve, JK ᵇ+ve ) phenotype corresponds to JKᵇ JKᵇ genotype
• (JKᵃ+ve, JK ᵇ+ve) phenotype corresponds to JKᵃ JKᵇ genotype
• (JKᵃ-ve, JK ᵇ-ve ) phenotype corresponds to no gene.

Antibodies

• Anti-JKᵃ and anti-JKᵇ are immune antibodies formed due to immunization by previous blood transfusion or pregnancy.
• They are IgG immune antibodies.
• React optimally at 37°C.
• They cannot fix complement, causing extravascular hemolysis.
• They can cross the placenta, causing HDN.

MNSs Blood Group System

Discovery

• Injecting guinea pigs with RBCs.
• Purifying the antibodies that occurred.
• Two types of antibodies were found after purification: Anti-M and Anti-N.
• Reacting these antibodies with human cells gives: +ve with anti-M implies M Ag, +ve with anti-N implies N Ag, +ve with anti-M N implies MN Ag.

Phenotype and Genotype

• M +ve phenotype corresponds to MM genotype.
• N +ve phenotype corresponds to NN genotype.
• MN +ve phenotype corresponds to MN genotype.

S and s Antigens

• Agglutination indicates that anti-S is from the same system.
• The S Ag and s Ag are structurally similar.
• Ss Ags are controlled by two allelic genes (S gene, s gene).

Phenotype and Genotype for MNSs

• M+ S+ phenotype implies MM SS genotype.
• M+S+s+ phenotype implies MM Ss genotype.
• M+s+ phenotype implies MM ss genotype.
• N+S+ phenotype implies NN SS genotype.
• N+S+s+ phenotype implies NN Ss genotype.
• N+s+ phenotype implies NNss genotype.
• M+N+S+ phenotype implies MNSS genotype.
• M+N+S+s+ phenotype implies MNSs genotype.
• M+N+s+ phenotype implies MNss genotype.

Antibodies

• Anti-M and anti-N are cold agglutinins (cold IgM).
• React best at 4°C but can react up to 15°C.
• They are immune antibodies, except for some naturally occurring forms of anti-N.
• They can fix complement, causing intravascular hemolysis and acute hemolytic transfusion reaction.
• They cannot cross the placenta and therefore do not cause HDN.

MN Antigens

• Relatively weak with no clinical importance except in paternity testing.

Anti-S and Anti-s

• Immune antibodies.
• IgG warm antibodies react at 37°C.
• Can cross the placenta, causing HDN.

Lutheran Blood Group System

Antigens

• Luᵃ and Lu ᵇ are the antigens.

Phenotype and Genotype

• Luᵃ+ve Lu ᵇ-ve phenotype implies Lu ͣ Lu ͣ genotype.
• Luᵃ-ve Lu ᵇ+ve phenotype implies Luᵇ  Luᵇ genotype.
• Luᵃ+ve Lu ᵇ+ve phenotype implies Luᵃ  Luᵇ genotype.
• Luᵃ-ve Lu ᵇ-ve phenotype implies either no gene or an inhibitor enzyme that stops the gene reaction.

Antibodies

• Anti-Luᵃ is an immune IgM cold antibody.
• Gives mixed-field agglutination characterized by morula agglutination with plenty of free cells.
• Anti-Luᵇ is an immune IgM cold antibody, sometimes IgG warm.

P Blood Group System

Antigen

• P is one antigen.

Antibodies

• IgM immune antibody.
• Reacts best at 4°C.
• Can fix complement, causing intravascular hemolysis and acute hemolytic transfusion reaction.
• Cannot cross the placenta and therefore cannot cause HDN

Donors

• Two types of donation: A- Volunteer blood donation system and B- Direct blood donation system.

Volunteer Blood Donation

• Panel of donors at a specific age, replaced as they age or become ill.
• Internationally recommended.

Direct Blood Donation

• Has two disadvantages: no reserve blood in the blood bank and recipients are sensitized against antigens of their own relatives, complicating organ transplantation.

Criteria of Blood Donor (WHO)

• Donor should be a healthy individual.
• Age limit (18 up to 55 years).
• Weight (at least 50kg for 450ml of blood + 45ml additional for testing HIV, Hepatitis).
• Body temperature should not exceed 37°C.
• Pulse should be normal (72 beats/min).
• Blood pressure should be normal (120/80).
• Hb level should not be lower than 13.5 in males and 12.5 in females.

Steps of Blood Donation

Medical Interview

• Usually held by a blood bank physician.
• Includes respiratory system, cardiac system, and measurement of temperature and pulse.
• Previous illnesses help decide whether to accept or defer a donor permanently or temporarily.

Permanent Deferral

• +ve HIV, hepatitis B or C, chronic disorders like diabetes, hypo or hypertension.

Deferral for 2 Months

• After minor surgery or tooth extraction.

Deferral for 6 Months

• Travel to an area of endemic malaria.
• Major surgery, after delivery.

Deferral for 13 Months

• After vaccination for measles, mumps, or rubella.

Screening Hb Level and Detection

• ABO and Rh D blood group system.

Blood Collection

• Donor placed in the supine position.
• Tourniquet applied on the forearm, and the site is cleaned with 70% ethanol.
• Enter the vein with a single vein puncture.
• Place the bag in a position lower than the donation, collecting 450 ml of blood.
• Blood should be mixed with the anticoagulant 2 times/minute.
• Put the blood in the refrigerator, either untested or safe blood.

Donor Reaction

Vasovagal Reaction

• At the sight of blood, donors start breathing rapidly, expelling large amounts of CO₂, leading to respiratory alkalosis.

Hematoma

• Escape of blood from blood vessels to surrounding tissue.

Hypotension

• More common in summer than winter.
• Immediately stop blood donation and raise legs on pillows.
• Give oral fluids.
• IV drips of normal saline.

Hypovolemic Shock and Death

Anti-Coagulants Used in Blood Bank

Acid Citrate Dextrose (ACD)

• Citrate salt acts as an anticoagulant by binding calcium, preventing blood clotting.
• Citric Acid maintains the acidic pH of blood during storage.
• Dextrose is a source of energy (nutrition).
• Shelf life: 3 weeks or 21 days.

Citrate Phosphate Dextrose (CPD)

• Prepared by adding a phosphate buffer to ACD to increase shelf life.
• Shelf life: 4 weeks or 28 days.

Citrate Phosphate Dextrose Adenine (CPA-A)

• Adenine is added to CPD, also to increase ATP production.
• Shelf life: 5 weeks or 42 days.

Heparin (Sodium-Potassium)

• Mainly used in special situations like intrauterine transfusion and exchange transfusion.
• Heparinized fresh blood collected should be used within 24 hours.

Blood Products

Benefits of Preparing Blood Products

• Avoids the waste of other products.
• Maximizes blood use by treating patients.
• Maintains the target level of different elements by using a relatively smaller volume.

One Unit of Whole Blood

• Volume: 520ml + 63ml of anticoagulant.
• Consists of RBCs + plasma only after 34 hours because granulocytes and platelets coagulation factors are significantly reduced after 48 hours.

When to Give Whole Blood

• Cases when both RBCs and plasma are required, such as acute blood loss, accidents, severe bleeding from GIT, urinary tract, uterus, surgery.

Blood Products from One Unit

• A- Cellular product and B- Plasma product

Cellular Product

• RBCs product, platelet concentrate, granulocyte concentrate

Plasma Component

• Fresh frozen plasma, cryoprecipitate, Factor VIII concentrate, Factor IX concentrate, anti-inhibitor coagulation complex, albumin, immunoglobulins.

Blood Bag Systems

• Blood bags are made of polyphenyle chloride, which contains small pores to allow gas exchange.

Single Bag System

• Used for the collection and transfusion of whole blood.

Double Bag System

• One mother bag contains the anticoagulant, and an empty daughter bag.
• Used for the preparation of two blood products: packed RBCs and fresh frozen plasma.

Triple Bag System

• One mother bag contains the anticoagulant, and two sisters or daughter bags: one containing SAG-M and another empty.
• Used to prepare blood products: packed RBCs, fresh frozen plasma, and platelet concentrate.

Steps to Prepare Blood Products Using a Triple Bag System

• Collect blood into the mother bag.
• Centrifuge at high speed to form packed RBCs and platelet-rich plasma.
• Transfer 250-300ml of platelet-rich plasma into the empty daughter bag.
• Transfer SAG-M from the daughter bag to the mother bag to form packed RBCs with 53% PCV.
• Separate the mother bag and store the packed RBCs at 4°C.
• Centrifuge the platelet-rich plasma using heavy speed to form aggregated platelets bottoms and platelet-poor plasma.
• Transfer all but about 50 ml of PPP onto the other sister bag and separate the two bags.
• PPP is then stored as FFP at -30°C for 6 months or -70°C for 12 months.
• Platelets button + 50ml of PPP is allowed to store for 1 hour at RTP to allow genetic disaggregation of platelets and then exposed at RTP and used within 5 days.