Six weeks after allogeneic bone marrow transplantation, a patient develops a maculopapular rash over palms and soles, watery diarrhoea, and rising bilirubin. Biopsy of involved skin shows apoptosis of basal keratinocytes with lymphocytic infiltrate at the dermoepidermal junction. Which cells mediate this condition?

• A Donor mature T cells recognising host alloantigens ✓
• B Host NK cells attacking donor haematopoietic cells
• C Donor B cells producing antibodies against host HLA
• D Host regulatory T cells suppressing donor engraftment

Explanation

Graft-versus-host disease occurs when immunocompetent donor T cells, mainly mature T cells in the graft, recognise recipient alloantigens as foreign and mount a cytotoxic response. The target organs are skin, gastrointestinal tract, and liver, matching the rash, diarrhoea, and cholestatic jaundice seen here. It requires a graft containing immunologically competent cells, an immunocompromised host, and histoincompatibility. Host NK cells and donor antibodies do not drive the classical acute GVHD triad.

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.