Immunology USMLE Step 1 Practice Questions
74 board-style USMLE Step 1 questions in Microbiology/Immunology. Each question shows the correct answer; create a free account for the full explanation and adaptive practice.
- USMLE Step 1 · easy25. A 37-year-old woman receives a red blood cell transfusion following postpartum hemorrhage. Within minutes, she develops fever (39.2°C), chills, flank pain, and dark urine. Vital…
- USMLE Step 1 · medium26. An 8 year old boy is brought to the physician because of frequent ear infections and progressive difficulty walking. His parents report that he often stumbles and has had severa…
- USMLE Step 1 · medium27. A 13-month-old girl with no fever (37.2°C), normal vital signs (HR 110/min, RR 28/min, BP 95/60 mmHg), and normal oxygen saturation receives a Haemophilus influenzae type b conj…
- USMLE Step 1 · medium28. A 27-year-old man presents with fever (39.2°C), cough, and dyspnea. Vital signs show BP 118/76, HR 102, RR 22, SpO2 88% on room air. Chest X-ray reveals bilateral infiltrates. B…
- USMLE Step 1 · medium29. A 4-month-old breastfed infant with recurrent sick contacts at home presents with minimal infections. Vital signs are normal (HR 140, RR 35, Temp 37.2°C). Physical examination r…
- USMLE Step 1 · hard30. A 22-year-old man presents with episodic dark urine, fatigue, and dyspnea. Vital signs show HR 102/min, BP 118/76 mmHg, RR 18/min. Laboratory studies reveal hemoglobin 9.2 g/dL,…
- USMLE Step 1 · hard31. A 19-year-old man presents with arthralgias and malar rash. Vital signs: BP 128/82, HR 92, RR 16, Temp 37.2°C, SpO2 98%. Labs reveal ANA 1:640 with anti-dsDNA antibodies; comple…
- USMLE Step 1 · medium32. A 6-year-old girl receives a protein-based vaccine booster. Six weeks later, she presents with high-affinity IgG antibodies against the vaccine antigen, confirmed by serum immun…
- USMLE Step 1 · easy33. A 6-year-old boy with sickle cell disease presents with fever (39.2°C), lethargy, and nuchal rigidity. Vital signs show HR 128/min, RR 28/min, BP 102/68 mmHg, and SpO2 98% on ro…
- USMLE Step 1 · medium34. A 9-year-old boy recently immigrated from a tropical region presents with chronic abdominal discomfort and fatigue. Vital signs show BP 95/60, HR 102, RR 20, Temp 37.2°C, SpO2 9…
- USMLE Step 1 · medium35. A 28-year-old researcher conducts an in vitro study exposing naive CD4+ T cells to peptide-bound MHC-II molecules presented by antigen-presenting cells deliberately engineered t…
- USMLE Step 1 · medium36. A 46-year-old woman with metastatic breast cancer (HR 92, BP 128/82, SpO2 98% on room air) receives trastuzumab, a monoclonal antibody against HER2. Two months later, imaging sh…
- USMLE Step 1 · medium37. A 34-year-old man with rheumatoid arthritis started infliximab 2 months ago. He presents with fever (38.9°C), weight loss, and productive cough. Vital signs show HR 98/min, BP 1…
- USMLE Step 1 · hard38. A 3-year-old boy who received BCG vaccine abroad develops disseminated infection with fever to 38.5°C, HR 108/min, and hepatosplenomegaly. He subsequently presents with recurren…
- USMLE Step 1 · medium39. A 28-year-old male veterinarian presents 2 hours after a bite from a stray raccoon with a bleeding puncture wound to the forearm. Vital signs: BP 128/82, HR 88, RR 16, Temp 37.2…
- USMLE Step 1 · medium40. A 10-month-old boy with DiGeorge syndrome presents for routine health maintenance. Vital signs are normal (BP 95/60, HR 110, RR 28, Temp 37°C, SpO2 98% on room air). Laboratory…
- USMLE Step 1 · medium41. A 41-year-old man undergoes allogeneic bone marrow transplantation for acute leukemia. Three weeks post-transplant, he develops diffuse maculopapular rash, watery diarrhea, and…
- USMLE Step 1 · medium42. A 52-year-old man with end-stage renal disease undergoes kidney transplantation. Within minutes, the graft becomes cyanotic and stops producing urine. Vital signs show BP 158/92…
- USMLE Step 1 · easy43. A 29-year-old woman presents with intensely pruritic vesicular lesions on her wrists and forearms 48 hours after hiking through poison ivy. Vital signs show BP 118/76, HR 82, RR…
- USMLE Step 1 · medium44. A 33-year-old man received equine-derived antitoxin following a snakebite. Eight days later, he presents with fever (38.8°C), diffuse arthralgias, urticarial rash, and mild dysp…
- USMLE Step 1 · medium45. A 26-year-old man presents with hemoptysis and dark urine over 5 days. Vital signs show BP 148/92 mmHg, HR 102 bpm, RR 22/min, temp 37.2°C, SpO2 94% on room air. Mild respirator…
- USMLE Step 1 · easy46. A 20-year-old woman with no prior shellfish exposure develops acute onset wheezing, diffuse urticaria, and angioedema within 3 minutes of ingesting shrimp. Vital signs show BP 8…
- USMLE Step 1 · hard47. A 6-year-old boy presents with recurrent sinopulmonary infections and chronic ulcerating skin lesions caused by respiratory viruses over the past 2 years. Vital signs show HR 10…
- USMLE Step 1 · hard48. A 7 month old infant has chronic diarrhea, oral candidiasis, and recurrent viral and bacterial respiratory infections. Flow cytometry shows normal B cell count, low CD4 positive…