MMSC 409 Exam 3 Questions and Verified
Answers
Lewis blood group Correct Answer: -antigens: Lea & Leb
-alleles: Le dominant and le recessive
-dominant Le codes for the production of a glycosyltransferase and Lea and Leb
antigens
-interacts with the secretor genes (Se and se)
-ISBT # 007
Le(a+b-) Correct Answer: white: 22%
black: 23%
Le(a-b+) Correct Answer: white: 72%
black: 55%
Le(a-b-) Correct Answer: white: 6%
black: 22%
Le(a+b+) Correct Answer: rare phenotype that is only seen in the Asian population
-Lewis b antigen usually out-competes Lewis a antigen for a place on the RBC
membrane, but in this case they are both present on the RBC
Lewis and Secretor gene interaction Correct Answer: -if someone has Le gene they
produce Lea and Leb antigens
,-if they are a secretor (Se) they will secrete Lea and Leb into their plasma and body
fluids, Leb will be detected on RBCs
-if they are not a secretor (se) they will only secrete Lea antigen into plasma and
body fluids, Lea antigen will be present on the RBCs
Lewis ABO and H interaction Correct Answer: -H gene codes for fucosyltransferase
that adds L fucose onto RBC membrane
-L-fucose sugar allows ABO antigenic sugars to attach to the RBC
-L-fucose allows Lea and Leb antigenic glycolipids to attach to the RBC membrane
-type O individuals have the highest amount of L-fucose attached to the RBC, so
they can have the greatest amount of Lewis antigens that attach to the RBC
lewis antigen synthesis Correct Answer: -Lea and Leb are produced by tissue cells
and get secreted into body fluids
-Lea and Leb that are secreted into the plasma are adsorbed onto the RBC
membrane and become RBC antigens
-lewis antigens in the body fluids= glycoproteins
-lewis antigens on the RBC membrane= glycolipids
lewis type Correct Answer: -Le= person produces Lea and Leb
-le= person does not produce lewis antigens
-Se= person secretes lewis antigens, ABO antigens and H antigen into body fluids,
RBCs will be type Leb
-se= non secretor, RBCs will be Lea
, Le(a-b-) phenotype Correct Answer: -lele genotype: person is unable to produce Lea
or Leb antigens
-Le(w) mutation: mutation in the Lewis gene that makes it impossible to produce
the antigens
-pregnancy: short term changes in phenotype can be seen due to anti-Lea or anti-
Leb that form in maternal circulation and disappear after the baby is born
lewis HDFN Correct Answer: NOT a cause of HDFN
-anti-Lea or anti-Leb that form during pregnancy are IgM antibodies that are too
large to cross the placenta
-if there were an IgG anti-lewis it would still not be that significant because
neonate RBCs have no lewis antigens (Le(a-b-)) until about 10 days of age
lewis HTR (hemolytic transfusion reaction) Correct Answer: reaction that is really
only seen in Le(a-b-) individuals because they are generally the only ones who form
Lewis antibodies
-IgM antibodies, not usually hemolytic
-IgG component that binds complement and reacts all the way through the AHG
phase of testing indicates that there is a high chance of hemolytic transfusion
reaction (provide antigen negative blood to individual)
lewis antibodies Correct Answer: -anti-Lea and anti-Leb
-IgM antibodies, mainly seen at IS phase of testing
-antibodies that react through the 37C and AHG phases of testing have an IgG
component and are likely to cause a HTR
-might not react with every single antigen positive cell
Answers
Lewis blood group Correct Answer: -antigens: Lea & Leb
-alleles: Le dominant and le recessive
-dominant Le codes for the production of a glycosyltransferase and Lea and Leb
antigens
-interacts with the secretor genes (Se and se)
-ISBT # 007
Le(a+b-) Correct Answer: white: 22%
black: 23%
Le(a-b+) Correct Answer: white: 72%
black: 55%
Le(a-b-) Correct Answer: white: 6%
black: 22%
Le(a+b+) Correct Answer: rare phenotype that is only seen in the Asian population
-Lewis b antigen usually out-competes Lewis a antigen for a place on the RBC
membrane, but in this case they are both present on the RBC
Lewis and Secretor gene interaction Correct Answer: -if someone has Le gene they
produce Lea and Leb antigens
,-if they are a secretor (Se) they will secrete Lea and Leb into their plasma and body
fluids, Leb will be detected on RBCs
-if they are not a secretor (se) they will only secrete Lea antigen into plasma and
body fluids, Lea antigen will be present on the RBCs
Lewis ABO and H interaction Correct Answer: -H gene codes for fucosyltransferase
that adds L fucose onto RBC membrane
-L-fucose sugar allows ABO antigenic sugars to attach to the RBC
-L-fucose allows Lea and Leb antigenic glycolipids to attach to the RBC membrane
-type O individuals have the highest amount of L-fucose attached to the RBC, so
they can have the greatest amount of Lewis antigens that attach to the RBC
lewis antigen synthesis Correct Answer: -Lea and Leb are produced by tissue cells
and get secreted into body fluids
-Lea and Leb that are secreted into the plasma are adsorbed onto the RBC
membrane and become RBC antigens
-lewis antigens in the body fluids= glycoproteins
-lewis antigens on the RBC membrane= glycolipids
lewis type Correct Answer: -Le= person produces Lea and Leb
-le= person does not produce lewis antigens
-Se= person secretes lewis antigens, ABO antigens and H antigen into body fluids,
RBCs will be type Leb
-se= non secretor, RBCs will be Lea
, Le(a-b-) phenotype Correct Answer: -lele genotype: person is unable to produce Lea
or Leb antigens
-Le(w) mutation: mutation in the Lewis gene that makes it impossible to produce
the antigens
-pregnancy: short term changes in phenotype can be seen due to anti-Lea or anti-
Leb that form in maternal circulation and disappear after the baby is born
lewis HDFN Correct Answer: NOT a cause of HDFN
-anti-Lea or anti-Leb that form during pregnancy are IgM antibodies that are too
large to cross the placenta
-if there were an IgG anti-lewis it would still not be that significant because
neonate RBCs have no lewis antigens (Le(a-b-)) until about 10 days of age
lewis HTR (hemolytic transfusion reaction) Correct Answer: reaction that is really
only seen in Le(a-b-) individuals because they are generally the only ones who form
Lewis antibodies
-IgM antibodies, not usually hemolytic
-IgG component that binds complement and reacts all the way through the AHG
phase of testing indicates that there is a high chance of hemolytic transfusion
reaction (provide antigen negative blood to individual)
lewis antibodies Correct Answer: -anti-Lea and anti-Leb
-IgM antibodies, mainly seen at IS phase of testing
-antibodies that react through the 37C and AHG phases of testing have an IgG
component and are likely to cause a HTR
-might not react with every single antigen positive cell
