🏥 USMLE Exam Prep

The major histocompatibility complex (MHC) class I molecules present:

A Extracellular antigens
B Intracellular (endogenous) peptides to CD8+ cytotoxic T cells
C Lipid antigens
D Only viral proteins

✓ Correct Answer: Option B

MHC I: found on all nucleated cells. Presents intracellular peptides (viral, tumor) to CD8+ T cells. MHC II: found on APCs (dendritic cells, macrophages, B cells). Presents extracellular antigens to CD4+ T cells.

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