LPMS Exam Questions and Answers With Verified Solutions 2025
The primary site of hematopoiesis changes location during development. In the fetus, by the eighth
month of intrauterine life, the primary site of hematopoiesis is in which of the following locations?
A.bone marrow
B.liver
C.spleen
D.thymus
E.yolk sac - ✔✔A. bone marrow
At what age does the thymus reach its maximal size?
A.During the first year of life
B.Teenage years (puberty)
C.Between 40 and 50 years of age
D.After 70 years of age - ✔✔B. Teenage years (puberty)
Which one of the following is an attribute of the innate, rather than the adaptive (acquired), arm of our
host defenses?
A.Is highly specific in its response to bacteria
B.Responds to viruses and fungi, but not bacteria
C.Exhibits memory following exposure to bacteria
D.Is part of our host defense against bacteria but not against fungi
E.Is as effective the first time it is exposed to bacteria as it is subsequent times - ✔✔E. Is as effective the
first time it is exposed to bacteria as it is subsequent times
A 4-year-old boy is referred to a specialist for the diagnosis of a possible immunologic problem. The child
has extremely elevated white blood cell counts, with a profound lymphocytosis. A biopsy performed on
a cervical lymph node reveals extreme hypocellularity in both cortical and paracortical areas. Absence of
which of the following leukocyte surface molecules could result in this clinical pictures?
A.Addressins
B.Chemokines
,C.Immunoglobulin
D.Integrins
E.L-selectins - ✔✔4E
L-selectins are the molecules found on the surfaces of lymphocytes that mediate their binding to the
high endothelial venules of hymph nodes. This is the means by which lymphocytes enter lymph nodes;
without these molecules, they would be unable to leave the blood. Thus they would rise in the blood to
extreme levels and be absent form their appropriate areas in the secondary lymphoid organs.
About spleen, which of the following statement is NOT correct?
A.It filters antigens out of the blood.
B.The periarteriolar lymphoid sheath (PALS) is rich in T cells.
C.It contains germinal centers.
D.It functions to remove old and defective red blood cells.
E.Lymphatic vessels draining the tissue spaces enter the spleen. - ✔✔E. Lymphatic vessels draining the
tissue spaces enter the spleen.
Which of the following differentiates an antigen from an immunogen?
A.An antigen is a foreign molecule
B.An antigen can cause the production of antibodies
C.An antigen does not always elicit an immune response
D.Antigens are usually proteins or polysaccharides
E.Antigens are capable of being bound by immunologic receptors - ✔✔C. An antigen does not always
elicit an immune response
*Which of the following is NOT true regarding effective immunogens?
A.Foreign to the host
B.Fairly large (molecular weight > 6000)
C.Chemically complex (e.g. proteins made of many nucleotide bases)
D.Requires a carrier-conjugate to cause the generation of antibodies - ✔✔D. Requires a carrier-
conjugate to cause the generation of antibodies
,Which of the following best describes penicillin, a hapten?
A.Large in size and can induce an immune response alone
B.Large in size and needs to be coupled to induce an immune response
C.Small in size and can induce an immune response alone
D.Small in size and needs to be coupled to induce an immune response - ✔✔D. Small in size and needs
to be coupled to induce an immune response
Hapten - ✔✔small molecule that has to bind to a larger molecule to form an antigen
Isograft - ✔✔use of identical twin's tissue
*A 28-year-old man was brought into court for nonpayment of child support. A 20-year-old woman
insists that he is the father of her child. The court suggests before hearing the paternity case that various
genetic tests be performed on the man, woman, and child. One of the sets of tests was for genetic
immunoglobulin identification. Which immunoglobulin marker would be useful in this case?
A.Allotype
B.Idiotype
C.IgA2
D.IgM
E.Isotype - ✔✔A. individuals of the same species
*A 30-year-old woman comes to the physician because of a fever of 38.4°C and a diffuse macular rash
on her torso. Her blood pressure is 91/51 mm Hg. The physician obtains a culture from her vagina that
shows catalase-positive, gram-positive cocci. Over the next few days, the rash on her torso
desquamates. Which of the following organisms is most likely responsible for this patient's symptoms?
A.Actinomyces israelii
B.Clostridium perfringens
C.Proteus mirabilis
D.Staphylococcus aureus
E.Streptococcus pyogenes - ✔✔D
Staphylococcus aureus is a gram-positive, catalase-positive coccus. It produces a superantigen called
toxic shock syndrome toxin. The toxin causes a disease characterized by fever, hypotension, and a
, diffuse macular rash that desquamates after a few days.Answer A is incorrect. Actinomyces israelii is a
filamentous organism that is part of the normal flora of the mouth and gastrointestinal tract. It does not
cause toxic shock syndrome.Answer B is incorrect. Clostridium perfringens is the organism responsible
for the development of gas gangrene. This organism is associated with contaminated wounds and not
with toxic shock syndrome.Answer C is incorrect. Proteus mirabilis is a common cause of urinary tract
infections and is not associated with toxic shock syndrome.Answer E is incorrect. Streptococcus
pyogenes, a gram-positive coccus, can also cause toxic shock syndrome. Unlike S. aureus, it is catalase-
negative.
A student has a genetic defect and cannot produce the J chain which is important in the structure of
some immunoglobulin molecules. Which of the following will most likely be observed in this individual?
A.a decrease in mature B cells
B.a decrease in mature T lymphocytes
C.a decrease in serum IgM
D.an increase in IgA in the intestine
E.an increase in serum IgM and decrease in IgE - ✔✔C. a decrease in serum IgM
*An antiserum containing IgG directed against a large protein antigen is treated with the enzyme pepsin.
After refrigeration overnight, the resulting supernatant is mixed with the protein antigen. This final
mixture is most likely to do which of the following?
A.Agglutinate the antigen
B.Bind complement
C.Bind phagocytic cells
D.Lose cross-linking ability
E.Precipitate the antigen - ✔✔E
IgG and F(ab')2 fragments both have a valence of 2 and can bridge between antigens. Soluble antigens
will them precipitate. Particulate antigens (e.g. RBC) will then clump together. (agglutinate).
Supernatant includes the soluble proteins (soluble antigen).
A 24-year-old primigravid woman develops an acute infection with Toxoplasma gondii during her first
trimester of pregnancy. Blood-borne antigens of the parasite spread throughout the fetal circulation.
The patient later delivers a full-term baby boy with no apparent sighs of in utero infection. A parasite-
specific ELISA for which of the following immunoglobulin isotypes would be the most appropriate test to
diagnose acute infection in the neonate?
A.IgA
The primary site of hematopoiesis changes location during development. In the fetus, by the eighth
month of intrauterine life, the primary site of hematopoiesis is in which of the following locations?
A.bone marrow
B.liver
C.spleen
D.thymus
E.yolk sac - ✔✔A. bone marrow
At what age does the thymus reach its maximal size?
A.During the first year of life
B.Teenage years (puberty)
C.Between 40 and 50 years of age
D.After 70 years of age - ✔✔B. Teenage years (puberty)
Which one of the following is an attribute of the innate, rather than the adaptive (acquired), arm of our
host defenses?
A.Is highly specific in its response to bacteria
B.Responds to viruses and fungi, but not bacteria
C.Exhibits memory following exposure to bacteria
D.Is part of our host defense against bacteria but not against fungi
E.Is as effective the first time it is exposed to bacteria as it is subsequent times - ✔✔E. Is as effective the
first time it is exposed to bacteria as it is subsequent times
A 4-year-old boy is referred to a specialist for the diagnosis of a possible immunologic problem. The child
has extremely elevated white blood cell counts, with a profound lymphocytosis. A biopsy performed on
a cervical lymph node reveals extreme hypocellularity in both cortical and paracortical areas. Absence of
which of the following leukocyte surface molecules could result in this clinical pictures?
A.Addressins
B.Chemokines
,C.Immunoglobulin
D.Integrins
E.L-selectins - ✔✔4E
L-selectins are the molecules found on the surfaces of lymphocytes that mediate their binding to the
high endothelial venules of hymph nodes. This is the means by which lymphocytes enter lymph nodes;
without these molecules, they would be unable to leave the blood. Thus they would rise in the blood to
extreme levels and be absent form their appropriate areas in the secondary lymphoid organs.
About spleen, which of the following statement is NOT correct?
A.It filters antigens out of the blood.
B.The periarteriolar lymphoid sheath (PALS) is rich in T cells.
C.It contains germinal centers.
D.It functions to remove old and defective red blood cells.
E.Lymphatic vessels draining the tissue spaces enter the spleen. - ✔✔E. Lymphatic vessels draining the
tissue spaces enter the spleen.
Which of the following differentiates an antigen from an immunogen?
A.An antigen is a foreign molecule
B.An antigen can cause the production of antibodies
C.An antigen does not always elicit an immune response
D.Antigens are usually proteins or polysaccharides
E.Antigens are capable of being bound by immunologic receptors - ✔✔C. An antigen does not always
elicit an immune response
*Which of the following is NOT true regarding effective immunogens?
A.Foreign to the host
B.Fairly large (molecular weight > 6000)
C.Chemically complex (e.g. proteins made of many nucleotide bases)
D.Requires a carrier-conjugate to cause the generation of antibodies - ✔✔D. Requires a carrier-
conjugate to cause the generation of antibodies
,Which of the following best describes penicillin, a hapten?
A.Large in size and can induce an immune response alone
B.Large in size and needs to be coupled to induce an immune response
C.Small in size and can induce an immune response alone
D.Small in size and needs to be coupled to induce an immune response - ✔✔D. Small in size and needs
to be coupled to induce an immune response
Hapten - ✔✔small molecule that has to bind to a larger molecule to form an antigen
Isograft - ✔✔use of identical twin's tissue
*A 28-year-old man was brought into court for nonpayment of child support. A 20-year-old woman
insists that he is the father of her child. The court suggests before hearing the paternity case that various
genetic tests be performed on the man, woman, and child. One of the sets of tests was for genetic
immunoglobulin identification. Which immunoglobulin marker would be useful in this case?
A.Allotype
B.Idiotype
C.IgA2
D.IgM
E.Isotype - ✔✔A. individuals of the same species
*A 30-year-old woman comes to the physician because of a fever of 38.4°C and a diffuse macular rash
on her torso. Her blood pressure is 91/51 mm Hg. The physician obtains a culture from her vagina that
shows catalase-positive, gram-positive cocci. Over the next few days, the rash on her torso
desquamates. Which of the following organisms is most likely responsible for this patient's symptoms?
A.Actinomyces israelii
B.Clostridium perfringens
C.Proteus mirabilis
D.Staphylococcus aureus
E.Streptococcus pyogenes - ✔✔D
Staphylococcus aureus is a gram-positive, catalase-positive coccus. It produces a superantigen called
toxic shock syndrome toxin. The toxin causes a disease characterized by fever, hypotension, and a
, diffuse macular rash that desquamates after a few days.Answer A is incorrect. Actinomyces israelii is a
filamentous organism that is part of the normal flora of the mouth and gastrointestinal tract. It does not
cause toxic shock syndrome.Answer B is incorrect. Clostridium perfringens is the organism responsible
for the development of gas gangrene. This organism is associated with contaminated wounds and not
with toxic shock syndrome.Answer C is incorrect. Proteus mirabilis is a common cause of urinary tract
infections and is not associated with toxic shock syndrome.Answer E is incorrect. Streptococcus
pyogenes, a gram-positive coccus, can also cause toxic shock syndrome. Unlike S. aureus, it is catalase-
negative.
A student has a genetic defect and cannot produce the J chain which is important in the structure of
some immunoglobulin molecules. Which of the following will most likely be observed in this individual?
A.a decrease in mature B cells
B.a decrease in mature T lymphocytes
C.a decrease in serum IgM
D.an increase in IgA in the intestine
E.an increase in serum IgM and decrease in IgE - ✔✔C. a decrease in serum IgM
*An antiserum containing IgG directed against a large protein antigen is treated with the enzyme pepsin.
After refrigeration overnight, the resulting supernatant is mixed with the protein antigen. This final
mixture is most likely to do which of the following?
A.Agglutinate the antigen
B.Bind complement
C.Bind phagocytic cells
D.Lose cross-linking ability
E.Precipitate the antigen - ✔✔E
IgG and F(ab')2 fragments both have a valence of 2 and can bridge between antigens. Soluble antigens
will them precipitate. Particulate antigens (e.g. RBC) will then clump together. (agglutinate).
Supernatant includes the soluble proteins (soluble antigen).
A 24-year-old primigravid woman develops an acute infection with Toxoplasma gondii during her first
trimester of pregnancy. Blood-borne antigens of the parasite spread throughout the fetal circulation.
The patient later delivers a full-term baby boy with no apparent sighs of in utero infection. A parasite-
specific ELISA for which of the following immunoglobulin isotypes would be the most appropriate test to
diagnose acute infection in the neonate?
A.IgA
