Blood Groups

Multiple Blood Group Antigens 30 common antigens More than 100 uncommon antigens Most of them are weak ABO system of antigens very strong Rh system also very strong

The ABO System Discovered in 1901 by Dr. Karl Landsteiner 4 Main Phenotypes (A, B, AB, O) ABO gene located on long arm of chromosome 9

ABO blood group system Two antigens (Agglutinogens) Agglutinogen A Agglutinogen B Two antibodies (Agglutinins) Agglutinin anti A or alpha (α ) antibody Agglutinin anti B or beta (β) antibody

ABO Antibodies A and B substances are the most common Antibodies produced to “non-self” antigen Produced after first few months of life A & B people have mainly IgM O people have IgG May fade in old age

ABO Antibodies

ABO antigens found on surface of the cell

ABO blood group system (Cont…) Four major groups Blood group A Agglutinogen A is present Blood Group B Agglutinogen B is present Blood group AB Both Agglutinogens A & B are present Blood group O None of the agglutinogens are present

ABO Blood Groups A - A antigen only B - B antigen only AB - Both A and B antigens O - Neither antigen

ABO Blood Group

ABO Blood Group

ABO Blood Group

ABO Blood Group

ABO Blood Group

ABO Markers (antigen and antibodies) Blood Group Markers ABO Markers (antigen and antibodies) Blood Type Antigen (blood group) Antibody % population A Anti-B 40 B Anti-A 10 AB A & B none 5 O None Anti-A & Anti-B 45

Antigens and antibodies of ABO blood Group system Landsteiner’s Law In ABO blood group system When one antigen is present on the cell membrane of RBCs, antibody which can react with this antigen is always absent. And when one antigen is absent in the cell membrane of RBCs, antibodies to this antigen are always present in the plasma.

Blood Group Identification ABO Identification A cells clump with anti-A B cells clump with anti-B AB cells clump with both O cells do not clump

Genotypes of blood groups Three genes: A, B & O Two of these genes are present, one on each of the paired chromosomes O gene is functionless and does not produce antigen O Both A & B genes always express in the form of Agglutinogen A and Agglutinogen B respectively

Genotypes of blood groups (Cont…) Six possible combinations of these genes called ‘Genotypes’ can result, i.e. AA, AO, BB, BO, AB & OO Four blood groups AA & AO will express as Blood Group A BB & BO will express as Blood Group B AB genotype will express as Blood Group AB OO genotype will express as Blood Group O Every human being belongs to one of these six genotypes and blood groups

ABO Genotypes and Phenotypes

Blood groups with their genotypes, antigens and antibodies AGGLUTINOGEN AGGLUTININ OO O None Anti A Anti B OA or AA A Anti B OB or BB B Anti A AB A & B

Origin of agglutinins Gamma globulins (like all other antibodies) Mostly IgM & IgG immunoglobulins Level at birth is almost ZERO and titre gradually increases after exposure to respective antigen Small amount of antigen A & B enter into the body via food and other routes & produce respective antibody if that antigen is absent on the cells.

Blood transfusion In blood transfusion Antigens of the donor are important. They should not be given to a person who has antibodies against these antigens The antibodies of the donor are NOT important They are diluted in recipient's plasma Or their concentration falls too low in storage

Blood transfusion The antigens in the recipient’s RBC are not important The antibodies in recipient’s plasma are important

Universal Donor and Recipient Group O Carries no A or B antigens Packed and processed units have little antibody Universal Recipient Group AB Patient has no anti-A or anti-B present Cannot lyse any transfused cells Beware: other antibodies may be present

Transfusion reactions Mismatched transfusion→ Transfusion reaction IgG is divalent IgM is polyvalent Reaction between Antigen & antibodies → Agglutination

AGGLUTINATION Donor antigens and recepient antibodies are important. Mismatched blood causes a transfusion reaction. RBCs of donor blood are agglutinated. Agglutination of recipient’s blood does not occur because plasma portion of the donor blood immediately becomes diluted by all the plasma of the recipient.

The titer of infused agglutinins decrease. On the other hand, small amount of blood infused cannot dilute recipient’s agglutinins so recipient’s antibodies can still agglutinate the mismatched donor cells.Eventually either Immediate hemolysis by hemolysins(IgM antibodies) Later hemolysis from phagocytosis of agglutinated cells.

Agglutination 14-34

Transfusion reactions Hemolysin antibodies are responsible for immediate hemolysis

Transfusion reactions Agglutination →Plugging of small blood vessels by clumps

Transmission of many disease Jaundice Renal shut down Transmission of many disease Hepatitis AIDS Infectious diseases

Hb ___bilirubin___excreted in bile by the liver Hb ___bilirubin___excreted in bile by the liver. Increased bilirubin ____jaundice. If liver function is normal, the bile pigment will be excreted into the intestines by the liver bile. Jaundice usually does not appear unless 400ml of blood is hemolyzed in less than a day.

Acute KIDNEY shut down: 1.An-Ab reaction___toxic substances from hemolyzing blood_____renal vasoconstriction. 2.Loss of circulating RBCs____circulatory shock. 3.Free Hb +haptoglobin__excess of Hb leaks through the glomerular membrane into the kidney tubules.----renal tubular blockage.______acute kidney shut down.

Choose the best response Q.1. In ABO blood group system: a)Blood group A has anti A antibodies. b)Blood group B has anti A antibodies. c)Blood group O has no antibodies. d)Blood group AB has anti A and anti B antibodies.

Q 2.In blood transfusion reaction: a)Blood of the donor can dilute recipient’s antibodies. b)Agglutination of the recipient’s blood occurs. c)RBC’s of the donor’s blood are agglutinated. d)Antigens of the recipient’s blood are important.

Q. 3. Regarding antibodies in ABO blood group system: a)These are of IgE type. b)Mostly are of IgG and IgM type. c)Level of antibodies are maximum at birth. d)Titer gradually decreases after exposure to respective antigens.

Q.4 Regarding antigens of ABO blood group system Blood group A has agglutinogen B on the cell membrane of RBCs. Blood group B has agglutinogen A on the cell membrane of RBCs. Blood group AB has agglutinogen A and B on the cell membrane of RBCs. Blood group O has agglutinogen A and B on the cell membrane of RBCs.

Thank-you Questions ??