In the context of transplant rejection, which of the following correctly describes the process of direct allorecognition?

• A Donor T cells recognize recipient MHC molecules
• B Recipient T cells recognize processed donor peptides presented by recipient MHC molecules
• C Recipient T cells recognize intact donor MHC molecules on donor antigen-presenting cells ✓
• D Recipient B cells produce antibodies against donor MHC peptides

Explanation

Direct allorecognition occurs when recipient T cells directly recognize intact donor MHC molecules on the surface of donor antigen-presenting cells. This is a high-frequency response early after transplantation. Indirect allorecognition involves recipient APCs processing and presenting donor MHC peptides via recipient MHC.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.