Immunology

Topics in this chapter

• Immune Cell Development and Markers
• Antigen Presentation and MHC
• B-Cell and Antibody Responses
• Innate Immunity and Complement
• Hypersensitivity and Immune Complexes
• Primary Immunodeficiency Disorders

Practice questions

1. Question 1Q-EAAC1E

   A 32-year-old man presents with recurrent sinopulmonary infections and bronchiectasis. Laboratory evaluation reveals profoundly low serum levels of IgG, IgA, and IgM, while circulating CD19+ and CD20+ B lymphocytes are present in normal numbers. T-lymphocyte counts and functions are normal. Which of the following is the most likely molecular defect responsible for this condition?

   1. A.Mutation in the Bruton tyrosine kinase (BTK) gene
   2. B.Mutation in the CD40 ligand (CD40L) gene
   3. C.Mutation in the AICDA gene encoding activation-induced cytidine deaminase
   4. D.Mutation in the TACI (TNFRSF13B) gene
   See the answer and solution
2. Question 2Q-7D152A

   Which of the following interleukins is the primary growth, survival, and differentiation factor for naive T cells and is essential for the generation and maintenance of regulatory T cells (Tregs)?

   1. A.Interleukin-1 (IL-1)
   2. B.Interleukin-2 (IL-2)
   3. C.Interleukin-4 (IL-4)
   4. D.Interleukin-17 (IL-17)
   See the answer and solution
3. Question 3Q-D0B483

   A 4-year-old boy presents with recurrent skin abscesses caused by Staphylococcus aureus and deep-seated fungal infections with Aspergillus. Nitroblue tetrazolium (NBT) test is abnormal (fails to turn blue), and dihydrorhodamine (DHR) flow cytometry test demonstrates a severe defect in neutrophil oxidative burst. Which enzyme complex is defective in this patient?

   1. A.Myeloperoxidase
   2. B.Phagocyte NADPH oxidase
   3. C.Glucose-6-phosphate dehydrogenase
   4. D.Inducible nitric oxide synthase
   See the answer and solution
4. Question 4Q-10142B

   During negative selection in the thymic cortex and medulla, developing thymocytes that recognize self-antigens presented by cortical and medullary thymic epithelial cells with high affinity undergo which of the following fates?

   1. A.Positive selection
   2. B.Clonal anergy
   3. C.Apoptosis (programmed cell death)
   4. D.Receptor editing
   See the answer and solution
5. Question 5Q-9F58AB

   A patient is evaluated for hereditary angioedema characterized by recurrent episodes of non-pruritic swelling of the face, extremities, and airway, without urticaria. Laboratory tests show low levels of C4 and decreased functional activity of C1 esterase inhibitor (C1-INH). Which of the following pathways is directly and constitutively overactivated in this condition?

   1. A.Alternative complement pathway
   2. B.Classical complement pathway
   3. C.Lectin pathway
   4. D.Terminal membrane attack pathway
   See the answer and solution