Immunology USMLE Step 1 Practice Question
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 T cells, and markedly decreased expression of MHC class II molecules on antigen presenting cells. Which of the following processes is most directly impaired?
Answer choices
- AMembrane attack complex formation
- BPresentation of endogenous antigen to cytotoxic T cells
- CPresentation of exogenous antigen to helper T cellsCorrect answer
- DV(D)J recombination
- EGeneration of reactive oxygen species in neutrophils
- FTAP1/TAP2 transporter deficiency causing absent MHC I presentation
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