BLOOD BANK EXAM 2 COMPREHENSIVE TEST
PAPER QUESTIONS AND SOLUTIONS
◉ Lewis Ab are often naturally occurring, and made by what
phenotype without any known RBC stimulus.
Answer: Le(a-b-)
◉ Do Lewis Ab typically cause HDFN.
Answer: No, not well developed on fetal RBC
◉ ________ may occur together and can be neutralized by the Lewis
substances present in plasma or saliva or with commercially
prepared Lewis substance.
Answer: Anti-Lea and anti-Leb
◉ Lewis antibodies occur quite frequently in the sera of pregnant
women who transiently exhibit the ............. phenotype.
Answer: Le(a-b-)
◉ Why is it relatively easy to find Le(a-) units.
Answer: 80% of the population are secretors. Obtaining donor units
that are typed Le(a-) with reagent antisera is generally not
,considered necessary for these patients, units that crossmatch
compatible in tests performed @ 37C are acceptable
◉ Why do people with Le(a-b+) RBC not make anti-Le-a?.
Answer: Small amounts of unconverted Le-a are present in their
plasma and saliva
◉ Lewis blood group substances present in transfused plasma
___________ lewis Ab in the recipient.
Answer: Neutralizes....that's why it is exceedingly rare for an anti-
Lea or anti-Leb to cause hemolysis or transfused RBC
◉ Both I and i are _______ prevalence antigens, but they are expressed
in reciprocal relationship that is developmentally regulated..
Answer: High.
◉ (I and i antigens)
At birth, infants are rich in ____, poor in ________
In adults, RBCs are rich in _____ and have only trace amounts of ______.
Answer: Infants: High i Low I
Adults: High I low i (adult i is rare, but excpress more i antigen than
cord RBCs)
, ◉ Common autoantibody in virtually all sera, although may require
testing @ 4C and/or against enzyme treated RBC to detect the
reactivity.
Answer: Anti-I, found in serum of many normal healthy people, is
benign and not associated with in vivo hemolysis....
-weak, naturally occurring, saline reactive IgM agglutinin with titer
<64 @ 4C
-Alloanti-i has never been described
-Autoanti-i is fairly rare but gives strong rxn with cord RBC and adult
i RBC, weaker with adult I
◉ Describe the reciprocal relationship of I antigen to i antigen.
Answer: I and i are not antithetical, but they are branched and linear
carbohydrate structure that are formed by the action of glycosyl
transferase.....synthesis of the two Ag are not controlled by the same
gene (I=027, i=li #207)
◉ Only very strong examples of autoanti-i are detected in routine
testing because....
Answer: Standard test cells (A1, A2, B, O, screening cells and panel
cells except cord RBC) have poor i expression
PAPER QUESTIONS AND SOLUTIONS
◉ Lewis Ab are often naturally occurring, and made by what
phenotype without any known RBC stimulus.
Answer: Le(a-b-)
◉ Do Lewis Ab typically cause HDFN.
Answer: No, not well developed on fetal RBC
◉ ________ may occur together and can be neutralized by the Lewis
substances present in plasma or saliva or with commercially
prepared Lewis substance.
Answer: Anti-Lea and anti-Leb
◉ Lewis antibodies occur quite frequently in the sera of pregnant
women who transiently exhibit the ............. phenotype.
Answer: Le(a-b-)
◉ Why is it relatively easy to find Le(a-) units.
Answer: 80% of the population are secretors. Obtaining donor units
that are typed Le(a-) with reagent antisera is generally not
,considered necessary for these patients, units that crossmatch
compatible in tests performed @ 37C are acceptable
◉ Why do people with Le(a-b+) RBC not make anti-Le-a?.
Answer: Small amounts of unconverted Le-a are present in their
plasma and saliva
◉ Lewis blood group substances present in transfused plasma
___________ lewis Ab in the recipient.
Answer: Neutralizes....that's why it is exceedingly rare for an anti-
Lea or anti-Leb to cause hemolysis or transfused RBC
◉ Both I and i are _______ prevalence antigens, but they are expressed
in reciprocal relationship that is developmentally regulated..
Answer: High.
◉ (I and i antigens)
At birth, infants are rich in ____, poor in ________
In adults, RBCs are rich in _____ and have only trace amounts of ______.
Answer: Infants: High i Low I
Adults: High I low i (adult i is rare, but excpress more i antigen than
cord RBCs)
, ◉ Common autoantibody in virtually all sera, although may require
testing @ 4C and/or against enzyme treated RBC to detect the
reactivity.
Answer: Anti-I, found in serum of many normal healthy people, is
benign and not associated with in vivo hemolysis....
-weak, naturally occurring, saline reactive IgM agglutinin with titer
<64 @ 4C
-Alloanti-i has never been described
-Autoanti-i is fairly rare but gives strong rxn with cord RBC and adult
i RBC, weaker with adult I
◉ Describe the reciprocal relationship of I antigen to i antigen.
Answer: I and i are not antithetical, but they are branched and linear
carbohydrate structure that are formed by the action of glycosyl
transferase.....synthesis of the two Ag are not controlled by the same
gene (I=027, i=li #207)
◉ Only very strong examples of autoanti-i are detected in routine
testing because....
Answer: Standard test cells (A1, A2, B, O, screening cells and panel
cells except cord RBC) have poor i expression
