Lecture 17 - Introduction to Blood Serology

Question 1

Blood group antigens?

Answer 1

glycoproteins and glycolipids present on surface of red cells, sometimes one endothelial surfaces (e.g. ABO), genetically determined

Question 2

Genetic control of blood groups?

Answer 2

protein determinants (Rh Kell), glycolipid determinants (ABO, lewis group)

Question 3

Functional aspects of blood group antigens

Answer 3

duffy blood group and malaria (some africans have Fya - Fyb -, indicating resistance to malaria infection), Mcleod phenotype (Kx null phenotype associated wih Chronic Granulomatous Disease)

Question 4

Blood groups and populations?

Answer 4

genetic drift, no biological advantage but clinical implications; fuck all polys but some whites hve RhD negative, 1% polys but essentially none whites have Kidd, U phenotype only occurs in african heritage

Question 5

Antibodies of blood groups?

Answer 5

IgM, IgG, IgA

Question 6

Naturally occuring antibodies?

Answer 6

IgM, glycolipid antigens, can activate compliment and destroys RBC intravascularly (first year of life, often bacterial trigger)

Question 7

Immune response antibodies?

Answer 7

IgG, glycoprotein, no complement or early phase only, extravascular RBC destruction

Question 8

ABO antigens?

Answer 8

phenotype determined by series of Glycosyltransferase enzymes, and H antigen for expression

Question 9

Biochemical structure of ABO antigens?

Answer 9

A - presence of N-acetylgalactosoamine; B - presence of extra D galactose; O - absence

Question 10

ABO mismatch?

Answer 10

can be fatal, intravascular haemolysis, renal failure, DIC

Question 11

Rh(D)?

Answer 11

important as highly immunogenic, genotype is autisomal dominant, dd is amorph (makes no changes, just absence)

Question 12

Anti-D?

Answer 12

fomed by Rh(D) negative individuals who are exposed, IgG antibody causing extravascular destruction of RBC, most common cause of haemolytic disease of the newborn

Question 13

Importance of minor blood group systems?

Answer 13

frequency of antigen in population, frequency of antibody production following antigen containing blood transfusion, ability of antibody to destroy transfused RBC

Question 14

Zeta potential?

Answer 14

RBC are negatively charged; IgM molecule larger than zeta poential therefore cause cross-linking leading to agglutination, IgG too small to produce cross linking, requires Anti-Human globulin

Question 15

Haemolytic Disease of the Newborn?

Answer 15

when maternal antibody crosses placenta resuling in destruction of foetal RBC, IgG, caused by anti-D, anti-c and anti-kell, reduced by immunoprophylaxis

Question 16

HFDN pathophysiology?

Answer 16

first pregnancy little antibodies are produced, however in second the antibodies ready to attack antigen of fetus, can cause stillbirth of post-partum jaundice and kernicterus

Question 17

Prevention of Rh(D) HDN?

Answer 17

anti-D immunoglobulin given following birth of RhD positive baby to negative mother, given during pregnancy following potentially sensitising event (abortion, termination, amniocentesis)

Question 18

ABO fetal mismatch?

Answer 18

antigens weakly expressed on fetus and widely distributed on placental tissue and absorb antibodies before reaching fetus