Intro to Blood Group Serology Flashcards
Genetic control of blood groups
1) Protein determinants: genes code for antigen itseld, Rh, Kell, Duffy
2) Glycolipids deteminants: Enzymes that add or remove carbs: ABO, Lewis
Significance of blood group antigens and antibodies
Presence of foreign blood, so antigens causes production of antibodies, typically IgG, IgM, IgA.
May be naturally occurring (no foreign red cell exposure, but bacteria with similar antibodies, ABO so anti- A e.g) or immune stimulated ( exposure to foreign red cells, so transfusion or pregnancy. Rh+ so anti Rh)
Red cell antibody characteristics
Naturally Occurring: Usually glycolipid antigen, IgM, sometime IgG, activated complement, red cell destruction intravasculalrly
Immune Stimulated: Glycoprotein, IgG, no to complement, only to C3, extravascular red cell destruction
ABO Antigens: found on RBC’s, epithelial cells, granulocytes
Transfusion with wrong type leas to _____ activation and IV ____, ___ failue and DIC
Phenotype of ABO antigens determined by series of _____ _____ enzymes. These add ___ to CSM
_ antigen needed.
A: N-acetylgalactosamine
B: D galactose
O: Nil
Antibodies form against antigens that ___ ____ present
OO 46.5%
AA/AO 40%
BB/BO 9%
AB 4.5%
Phenotype of ABO antigens determined by series of glycosyl transferase enzymes. These add carb to CSM
H antigen needed.
A: N-acetylgalactosamine
B: D galactose
O: Nil
Antibodies form against antigens that ARE not present
OO 46.5%
AA/AO 40%
BB/BO 9%
AB 4.5%
Rh blood group system. Only on RBC’s. First bit not fill in the gaps.
If you transfuse D+ into a D- person, they will form ____ antibodies.
These do not activate ____ (IgG) but cause cell death _____
Common cause of haemolytic disease of the ____ . Thus would never transfer ___ red cells to ___ female of child bearing age due to anti-D risk
Caucasian: __% +ve, __%-ve
Poly: __-__% +ve
Rh(D) most important antigen. Either Positive or negative
SO DD or Dd is positive. dd neg. (amorph, odes for nothing)
If you transfuse D+ into a D- person, they will form anti-D antibodies.
These do not activate complement (IgG) but cause cell death extravascularly
Common cause of haemolytic disease of the newborn. Thus would never transfer D+ red cells to D- female of child bearing age due to anti-D risk
Caucasian: 83% +ve, 17%-ve
Poly: 98-99% +ve
Expanded Rh system
Includes D and d, E and e, C and c
Used for family studies and donor searches
Clinical importance of minor blood group systems
Kell, Kidd, Duffy
- Frequency of antigen in population
- Frequency of antibody production floowing transfusion of red cells containing antigen (immunogenicity)
- ability of antibody to destroy transfused cells
Haemolytic disease of the newborn
Occurs when maternal ___ crosses in fetal circulation, foetal red cell destruction. (can be when fetus is __, or transfused with __)
Always involves ___ (IgM won’t cross)
Frequently due to ____ antibodies
Frequency decreased by _______
In severe case, causes ___ ____. More often, ____ (brain damage from jaundice)
Immunoprophylaxis: Use of ____ immunoglobulin at time of delivery. This will lead to clearance of __ red cells during haemorrhage, and prevent primary immune response.
Occurs when maternal antibody crosses in fetal circulation, foetal red cell destruction. (can be when fetus is D+, or transfused with D+)
Always involves IgG (IgM won’t cross)
Frequently due to anti-D antibodies
Frequency decreased by immunoprophylaxis
In severe case, causes hydrops fetalis. More often, kernicterus (brain damage from jaundice)
Immunoprophylaxis: Use of Ant-D immunoglobulin at time of delivery. This will lead to clearance of D+ red cells, and prevent primary immune response.
ABO grouping and haemolytic disease
Incompatibility common, but disease rare due to
- AB antigens weakly expressed in newborn
- AB antigens widely seen i placenta, and absorb anti-A and B antibodies
