BB CIULLA (w/RATIO) EXAM QUESTIONS
AND ANSWERS
Most blood group antibodies are of what immunoglobulin classes?
A. IgA and IgD
B. IgA and lgM
C. IgE and lgD
D. IgG and lgM - ANSWER D. IgG and lgM
D. The body makes five different immunoglobulins: IgA, IgD, IgE, IgG,
and IgM. IgG makes up about 80% of the total serum immunoglobulin.
Although IgA is more abundant than IgM (13% versus 6%), IgM is more
common as a blood group antibody.
The following family study is performed:
Mother /Father / Child 1/ Child 2
K+k+/K-k+/K+k-/K-k+
All other indications are that these children are both the products of this
mating. Possible explanations for these results would include
A. A dominant inhibitor gene has been passed to child 1
B. Father has one k gene and one K° gene
C. Father has the McLeod phenotype
D. Mother has a cis-Kk gene - ANSWER B. Father has one k gene and
one K° gene
B. From his phenotype, the father appears to be homozygous kk
genetically. However, he is actually K°k and has passed the K° gene to
child 1. The K° gene at the Kell locus does not appear to result in the
formation of any Kell system antigens. Child 1 has the genotype K°K,
having received the K gene from the mother, and has a phenotype
expressing on the K antigen. Child 2 can have either the genotype kk or
K°k, with the mother contributing a k gene and the father either K° or k.
The McLeod phenotype would result in weakened expression of K or k
,antigens. There has been no cis-Kk gene discovered, nor any dominant
inhibitor gene that represses the expression of Kell system genes.
Which of the following blood groups reacts least strongly with an anti-H
produced in an A1B individual?
A. Group O
B. Group A2B
C. Group A2
D. Group A1 - ANSWER D. Group A1
D. All red blood cells contain some amount of H substance. The only
exception is the very rare Oh (Bombay) individual because these
persons lack the H gene that codes for H substance. Group O cells
contain the most H substance, and A1B cells contain the least amount of
H substance. The order of decreasing reactivity with anti-H is: O > A2 >
A2B > B > A1 > A1B
How many genes encode the following Rh antigens: D, C, E, c, e?
A. One
B. Two
C. Three
D. Four - ANSWER B. Two
B. Two genes control Rh antigen activity. RHD controls the expression
of D antigen, and RHCE determines the C, E, c, and e antigens. RHD is
absent or inactive in D-negative individuals. Alleles of RHCE are RHCe,
RHcE, and RHce. The RH is often dropped (for example CE, Ce, cE,
ce).
A patient arrives in the OB clinic 3 months pregnant. This is her first
pregnancy, and she has never been transfused. Her prenatal screen
includes the following results:
Cell Typing Results: Anti-A 0, Anti-B 0
Serum Typing Results: A1 cells 4+, B cells 4+
____SC I / SC II / Auto-Control
IS: 4+ / 4+ / 0
,37: 4+ / 4+ / 0
AHG: 4+ / 4+ / 0
CC: __/ __/ Pos
The test results could be due to
A. Cold autoantibody
B. Inheritance of sese genes
C. Inheritance of hh genes
D. Rouleaux - ANSWER C. Inheritance of hh genes
C. This individual does not have a cold autoantibody, as demonstrated
by the negative autocontrol at all phases of testing. Being a nonsecretor
does not affect the ABO or Rh typing, nor will it cause the appearance of
unexpected antibodies in the patient's plasma. Rouleaux is ruled out
because reactions are still seen at AHG after all of the patient serum or
plasma has been washed away. Of the choices given, the most likely is
that the patient is a Bombay phenotype individual, having inherited one h
gene from each parent. The only other possibility is that the patient is a
group O with a strong unexpected antibody or antibodies in his/her
serum; however, that was not one of the choices given as an answer.
A patient arrives in the OB clinic 3 months pregnant. This is her first
pregnancy, and she has never been transfused. Her prenatal screen
includes the following results:
Cell Typing Results: Anti-A 0, Anti-B 0
Serum Typing Results: A1 cells 4+, B cells 4+
____SC I / SC II / Auto-Control
IS: 4+ / 4+ / 0
37: 4+ / 4+ / 0
AHG: 4+ / 4+ / 0
CC: __/ __/ Pos
If the patient's RBCs were tested against anti-H lectin and did not react,
this person would be identified as a(an)
A. Acquired B
B. Oh phenotype
C. Secretor
D. Subgroup of A - ANSWER B. Oh phenotype
, B. Bombay (Oh) individuals' red blood cells not only lack A and B
substances, but they also lack H substance. Bombays are genetically hh
and, therefore, are unable to produce the precursor H substance upon
which the A and B transferases act to produce A and B substances. In
their serum, they will have anti-A, anti-B, anti-A,B, and an equally strong
anti-H, which will react with normal group O cells. Neither O nor Oh red
blood cells react with anti-A,B or anti-Aj lectin. However, Oh red blood
cells give a negative reaction with anti-H lectin, whereas O cells are
positive, allowing differentiation of the two.
If a person has the genetic makeup Hh, AO, LeLe, sese, what substance
will be found in the secretions?
A. A substance
B. H substance
C. Lea substance
D. Leb substance - ANSWER C. Lea substance
C. The Le gene codes for a transferase enzyme, L-fucosyl transferase,
which attaches fucose to the subterminal sugar on the Type 1 precursor
substance producing Lea substance. This occurs independently of the
ABH secretor status. For Leb as well as ABH substances to be present
in the secretions, both the Se gene and the Le gene must be present.
The Se gene produces a transferase that attaches a fucose to the
terminal sugar on precursor substance, forming H substance in the
secretions. Type 1H and Type 2H are the precursors for A and B
substance. The Le gene can act upon Type 1H as well to form Leb
substance; therefore, a nonsecretor who has a Le gene will only secrete
Lea, whereas a secretor will secrete a little Lea and a lot of Leb
substance.
The following results were obtained when typing a patient's blood
sample.
Cell Typing Results: Anti-A 4+, Anti-B 2+
Serum Typing Results: A1 cells 0, B cells 4+
The tech suspects that this is a case of an acquired B antigen. Which of
the following would support this suspicion?