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Microbiology and Immunology

Host immune response Practice Questions

20 free Host immune response practice questions for the USMLE Step 1, each with the correct answer and a detailed explanation. Open any question below, or take the full set as an interactive quiz.

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All Host immune response questions

20 questions
  1. Q1. A patient is infected with an intracellular pathogen. Which immune component is most important for clearing this infection?
  2. Q2. A newborn receives maternal IgG antibodies through the placenta. What type of immunity does this represent?
  3. Q3. A patient develops fever and neutrophilia during acute bacterial infection. Which cytokine is primarily responsible for neutrophil recruitment?
  4. Q4. Which immunoglobulin is predominantly produced during a secondary immune response?
  5. Q5. Complement activation via the classical pathway requires which event?
  6. Q6. A patient with parasitic worm infection shows elevated eosinophil levels. Which immunoglobulin drives eosinophil activation?
  7. Q7. Natural killer (NK) cells primarily kill which type of cells?
  8. Q8. Which cytokine is most important for inducing fever during infection?
  9. Q9. A patient with recurrent Neisseria infections is found to have a complement deficiency. Which component is most likely deficient?
  10. Q10. Which immune cells are essential for granuloma formation in tuberculosis?
  11. Q11. A patient receives a booster vaccine and mounts a rapid, robust immune response. Which cells are primarily responsible?
  12. Q12. Type I interferons (IFN-α, IFN-β) help control viral infections by which mechanism?
  13. Q13. Which immunoglobulin is most effective at neutralizing pathogens on mucosal surfaces?
  14. Q14. A patient with CGD (chronic granulomatous disease) has impaired killing of catalase-positive organisms. Which enzyme is deficient?
  15. Q15. Which cytokine stimulates class switching to IgE in allergic responses?
  16. Q16. Which pattern recognition receptor detects LPS from Gram-negative bacteria?
  17. Q17. A patient with viral hepatitis develops hepatocyte apoptosis mediated by perforin and granzyme. Which cells are responsible?
  18. Q18. Which cell type presents antigen on MHC II molecules to CD4+ T cells?
  19. Q19. A patient with helminth infection shows elevated IL-5. Which function does IL-5 primarily support?
  20. Q20. A patient vaccinated with a live attenuated virus develops long-lasting immunity. What is a key advantage of live vaccines?