1. BLOOD GROUPS
All cells have inherited combination of proteins, glycoprotein & glycolipids on their surfaces.
These functions as antigens that enable of our immune system to distinguish our cells from foreign
invaders.
Part of the immune system is to produced γ-globulins calle antibodies to combat foreign invaders.
In blood typing the antigens of RBC surface are called agglutinogens, because they are partially
responsible for RBC agglutination I mismatched transfusions.
The plasma antibodies that react against them are called agglutinins
Carl Lansteiner in 1900 reported that human population could be divided into 4 groups on the
basis of blood types
These blood types were named A,B,AB & O & called ABO & Rh system
At least 001 blood groups are known but ABO & Rh system more important from clinical point of
view. The other blood groups are MN, Duffy,Kell, Kidd & lewis group
BLOOD GROUP SYSTEM;
Two antigens type A & B occurs on the surface of RBCs that cause most of the transfusion reactions.
As these antigen are inherited , people have neither of them on their on their cells, they have one or
they have both simultaneously
2 genes one on each of 2 paired chromosomes determines the O-A-B blood type.
These genes can be any one of three types, but only one type on each of the 2 chromosome: Type
O, Type A Or Type B.
Type O is either function less , therefore it causes no significant type O antigen on the cell
Type A & B causes strong agglutinogens on the cells.
Each person possess any one of the following 6 genotype combinations
OO,OA,OB,AA,BB& AB
AGGLUTININS OR ANTIBODIES
The agglutinins are gamma globulins & most of them are IgM & IgG type.
Their quantity at the time of birth is zero, but at the age of 2-8 months the infants starts producing
antibodies. i.e with antigen A , contains Anti B antibody etc
AGGLUTININS OR ANTIBODIES
If a person contains antigen A , then antibodies known as anti –B agglutinins develops in plasma
Similarly with antigen B, anti A antibody develops in plasma.
And if no antigen (blood group O) then anti A & B antibody develops in plasma
If a person contains both A & B antigens , than no antibodies present in plasma.
Rh BLOOD TYPES
Along with ABO blood group system the Rh blood type system is also very important in transfusion
of blood.
Discovered in 1940 is a blood group system use to find out that a person is Rh positive or Rh
negative.
Unlike the antibodies of ABO system , anti-D antibodies do not develop without exposure of a D-
negative person to a D positive cell by transfusion or entrance of fetal blood to a maternal blood
It primarily contains C,D& E antigens, although it contains many more.
D is more antigenic component & Rh positive means that the person has D antigen.
99% of Asians D-positive
2. Rh Blood Types
• Also important in blood transfusion along with ABO system
• In ABO system antibodies develops spontaneously whereas in Rh System, spontaneous antibodies
never develops.
• Instead the person first exposed to Rh antigen (by transfusion of blood containing antigens) that
results in formation of agglutinins
Erythrobalstosis fetalis (hemolytic disease of new born)
• Characterize by agglutination & phagocytosis of fetal RBCs.
• In most instances mother is Rh negative & father is Rh positive
• Baby inherit Rh positive from father
• Mother develops anti Rh antibodies from exposure to baby’s Rh antigen.
• Now mothers antibodies diffuses from placenta into the fetus & causes RBCs agglutination.
• Hemolysed RBC releases hemoglobin into the blood
• Fetal macrophage convert hemoglobin into bilirubin results in jaundice
Clinical; picture of erthroblastosis fetalis
• Baby born is jaundiced , anemic
• Rh antibodies circulate for 2 months in infants blood.
• Destroying more & more RBCs
• Hemopoeitic tissues attempt to replace RBCS & produced large & Immature (blast ) cells .
• Permanent mental impairment may occurs due to deposition of bilirubin in brain cells
(kernictrerus)
• Death may occur due to severe anemia. Treatment
• Exchange transfusion
• Replaced neonates Rh positive blood with 400 ml of Rh negative blood
• Procedure should be repeated several times during the first week s mainly to keep the level of
bilirubin at lower side to prevent kernicterus
• Aftrr this Rh positive blood of fetus is repalced again in 4-6 weeks by this time anti Rh agglutinin
that comes from mother would have been destroyed
Mismatch transfusion reactions
• If donor for e.g with blood group A is transfused by a blood group B , transfusion reaction is likely
to occur.
• Reaction occurs between RBCs of donor & antibodies of recipient
• Transfusion reaction causes immediate hemolysis releasing hemoglobin
• Released hemoglobin is converted into bilirubin by macrophages & later excreted in bile
• Increased bilirubin level may caused jaundiced
Acute renal shut shown
• One of the lethal outcome of transfusion reactions begin within few minutes to few hours until the
patient dies of renal failure.
• Antigen antibody reaction released toxic substances from hemolyzed blood causes intense renal
vasoconstriction.
• Loss of circulating RBCs & along with toxic substances released from RBCs causes circulatory shock
• Blood pressure decreases
• Renal blood flow & urinary output decreases.
• Thus combined effect of renal vasoconstriction , circulatory shock causes acute renal shut down
