WEEK 3: Antibody Identification

Question 1

what percentage of the population are alloantibodies found?

Answer 1

0.3-38%

Question 2

what is an alloantibody?

Answer 2

Alloantibodies are immune antibodies that are only produced following exposure to foreign red blood cell antigens.

Question 3

what mechanism involving antibodies can reduce the lifespan of a rbc?

Answer 3

activation of complement or adherence to Fc and compliment receptors on cells of monocyte

Question 4

what is a ‘clinically significant’ antibody?

Answer 4

– Antibody is capable of binding to its corresponding antigen and sensitising the red cell – it may activate complement
– Antibodies that are capable of causing patient morbidity due to the accelerated destruction of a significant proportion of transfused red cells
– One that shortens the survival of transfused red cells and/or causes HDFN

Question 5

what are the characteristic properties of a red cell antibody investigation panel?

Answer 5

• Identify a single antibody
• Separate common mixtures– If possible in a single pass
• Not give the same pattern of results with two different antibodies
• Give “confidence” in the findings

Question 6

what antibodies are significant for HDFN?

Answer 6

anti-D, anti-c, anti-K
Kidd system
Duffy system
anti-M

Question 7

what does the indirect antiglobulin technique detect?

Answer 7

37 degree C active antibodies
IgG antibodies
Complement fixing
all Rh antibodies

Question 8

what is the principle of an indirect antiglobulin technique?

Answer 8

antibody and known phenotype on rbc are incubated together at 37 degrees C. Sensitises rbcs
AHG is added to bind Fc region of antibody and rbc - usually 12 mm gap. This causes agglutination

Question 9

why is anti-human globulin (AHG) added in IAT?

Answer 9

to bind Fc region of antibody and rbc - usually 12 mm gap. This causes agglutination