BLOOD BANK EXAM 2 ACTUAL QUESTIONS
AND CORRECT ANSWERS
◉ It was originally thought that Le-a and Le-b were antithetical, but
we now know that they result from.....
Answer: interaction of two fucosyltransferases encoded by
independent genes, Le and Se
◉ The ______ gene must be present for a precursor substance to be
converted to Le-a, but the ______ gene must also be present for
conversion to Le-b.
Answer: Le, Se
◉ Le(a+b-) are from ABH........
Answer: Non-secretors
◉ Le(a-b+) RBCs are from ABH.....
Answer: secretors
◉ Le(a-b-) RBC are ABH.......
Answer: secretors or non-secretors
,◉ Define the interaction of Lewis genes with ABO, H, and secretor
genes.
Answer:
◉ List substances presents in secretions and the Lewis phenotypes
based on a given genotype.
Answer:
◉ Lewis antigens are not expressed on......., and are often diminished
during pregnancy. They are found on.......
Answer: -cord RBCs
-lymphs, platelets, other tissues such as pancreas, stomach,
intestine, skeletal muscle, renal cortex, adrenal glands, and if soluble,
in saliva as glycoproteins
◉ Lewis Ag enzyme resistance.
Answer: -Resist treatment with ficin and papain, DTT, and glycine-
acid EDTA
◉ Lewis Ab type.
Answer: Generally IgM, don't cross placenta
◉ 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
AND CORRECT ANSWERS
◉ It was originally thought that Le-a and Le-b were antithetical, but
we now know that they result from.....
Answer: interaction of two fucosyltransferases encoded by
independent genes, Le and Se
◉ The ______ gene must be present for a precursor substance to be
converted to Le-a, but the ______ gene must also be present for
conversion to Le-b.
Answer: Le, Se
◉ Le(a+b-) are from ABH........
Answer: Non-secretors
◉ Le(a-b+) RBCs are from ABH.....
Answer: secretors
◉ Le(a-b-) RBC are ABH.......
Answer: secretors or non-secretors
,◉ Define the interaction of Lewis genes with ABO, H, and secretor
genes.
Answer:
◉ List substances presents in secretions and the Lewis phenotypes
based on a given genotype.
Answer:
◉ Lewis antigens are not expressed on......., and are often diminished
during pregnancy. They are found on.......
Answer: -cord RBCs
-lymphs, platelets, other tissues such as pancreas, stomach,
intestine, skeletal muscle, renal cortex, adrenal glands, and if soluble,
in saliva as glycoproteins
◉ Lewis Ag enzyme resistance.
Answer: -Resist treatment with ficin and papain, DTT, and glycine-
acid EDTA
◉ Lewis Ab type.
Answer: Generally IgM, don't cross placenta
◉ 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
