Immunology Step 1 QBank

In the Haemophilus influenzae type b (Hib) vaccine, the polyribitol phosphate capsule of the organism is covalently conjugated to the diphtheria toxoid. Following inoculation, helper T (TH) lymphocytes will be attracted to the injection site. The idiotype of the specific responding TH cells will bind to which of the following molecules?

A 6-year-old boy is being evaluated by a pediatric specialist after his primary pediatrician admits him to the hospital for his third bout of pneumonia in a year. Specific serum tests reveal the presence of low levels of IgM and no IgG or IgA antibodies. T cell levels and responses are normal. This patient most likely has a dysfunction in the expression of which of the following molecules?

A 6-year-old male is brought to his pediatrician because of fatigue, bone pain, and easy bruising. A blood film demonstrates abnormally high numbers of mononuclear cells. Flow cytometry shows that the cells are TdT positive and possess cytoplasmic mu heavy chains. What is the stage of differentiation of these cells?

A male neonate delivered at 37 weeks’ gestation is small for gestational age. The infant suffers a convulsion within an hour of delivery.  He displays several facial anomalies, including wideset eyes, low set ears, and a shortened philtrum. A systolic flow murmur is present. Which of the following is the most likely cause of this infant’s condition?

A researcher is performing experiments addressing the impact of specific cytokines on immune responses. In one experiment, she treats mice with an antibody that blocks the function of IL12.  The mice would be expected to show most increased susceptibility to which of the following pathogens?

A 40-year-old male has been positive for HIV infection for the past 10 years. He has been carefully maintained on an antiretroviral “cocktail” since his diagnosis, and, at this year’s physical, his CD4 cell count is 890/mm3. His physician has elected to change the drugs in the regimen four times over the course of his infection. What is the best basis on which to judge the efficacy of an antiretroviral regimen?

A 50-year-old Philippine immigrant complains of loss of sensation in his fingers. On examination, he has a small number of nodular lesions on the skin of his hands and face. Needle biopsy of one of these lesions reveals granulomatous inflammation with a small number of acid-fast bacilli found inside macrophages. Which of the following would be the most important immune response to help this patient clear his infection?

A 35-year-old female seeks the advice of her physician complaining of joint pain for the last two months. She is a gardener at the local botanical gardens and has noticed increasing pain when she kneels or squats. Her cheeks have been red for a few weeks and she has noticed that her arms and neck have been more sun-sensitive this summer, as well. Laboratory analysis is significant for anti-DNA antibodies and antiphospholipid antibodies. Which of the following is most likely to be found in a needle biopsy of an affected joint?

A 13-year-old Syrian refugee with fever, aching ankle and knee joints, and a rash is presented to an urgent care center by his mother. He indicates that one month ago he missed school due to a sore throat. The rash on his trunk and arms is characterized by flat, red papules with raised, red edges. Which of the following findings would be helpful in confirming the most likely diagnosis?

A sample of lymphocytes is treated with fluorescently-labeled monoclonal antibodies against CD4 and CD8 and passed through the fluorescence-activated cell sorter. The results are shown above. What is the most likely source of these cells?

A family is evaluated at a genetic testing center for a genetic inability to produce complement component 4. Generation of the membrane attack complex in these individuals would depend on activation of which of the following?

A knockout mouse strain is developed in which RAG genes are deleted. A mouse of this strain is sacrificed, and its peripheral blood leukocytes are subjected to immunophenotyping by fluorescence-activated cell sorter. Which of the following is the most likely finding?

A 43-year-old woman visits her physician for a routine physical. She has noticed a 10-lb weight gain without any perceived change in diet or exercise. She complains that she feels cold all the time. On examination, her thyroid is enlarged, firm, and painless. Thyroid-stimulating hormone levels are elevated and T4 levels are depressed. Serum is positive for the presence of antithyroid peroxidase and antithyroglobulin antibodies. What is the mechanism of this disease process?

A 4-month-old infant is hospitalized with pneumonia. He has had several ear infections and 1 previous bout of pneumonia since birth. Laboratory analysis reveals marked neutropenia, and a blood film reveals that his neutrophils, eosinophils, and granulocytes have giant granules. What other finding would be noted in patients with this genetic defect?

Two months after receiving a liver transplant for alcoholic cirrhosis, a 59-year-old man presents to his hepatologist complaining of abdominal pain. He admits that he occasionally forgets to take his anti-rejection medication. Serum tests reveal increased AST and ALT. The hepatologist orders a liver biopsy, which returns a diagnosis of acute cellular rejection. What immunologic mechanism underlies this process?

A researcher is studying the immune responses generated against vaccines. She is most interested in tracking the development of long-lived immunity against poliovirus. She will be collecting blood samples from persons with a documented history of polio vaccination. Polio-specific, long-lived immunity in which cell type will be present in individuals who were vaccinated with the Sabin vaccine but absent in those vaccinated with the Salk vaccine?

A 45-­year-­old woman with severe rheumatoid arthritis is started on infliximab therapy. This therapy has been shown to increase the production of interleukin­-10. Which of the following is likely, therefore, to become most diminished in this patient?