
🧠 T-Cell Development and Selection for USMLE Step 1: From Stem Cell to Self-Tolerance
Master T-cell maturation for Step 1 — understand thymic selection, CD4/CD8 differentiation, and key immunodeficiencies.

🧠 MHC I vs MHC II for USMLE Step 1: Antigen Presentation, T-Cell Types, and Diseases
Differentiate MHC I and II pathways for Step 1 success. Learn their structure, function, antigen processing, and clinical relevance with KOTC visuals.