This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
Cells responsible for GVHD is ? 
Select and explain. 
A. Immunocompetent T cell donor, B. Immunocompetent T Cell recipient, C. Immunocompetent B cell donor, D. Immunocompetent B cell donor
A: Immunocompetent T cell donor
Answer: A: Immunocompetent T cell donor 
Explanation: Ans. is 'a' i.e., Immunocompetent T-cell donor Graft- versus-host disease (GVHD) :? GVHD occurs when immunologically competent cells (T cells) or their precursors are transplanted into immunologically crippled recipients, and the transferred cells recognize alloantigens in the host and attack host tissues. Most commonly involved tissues in Graft versus host disease :- Liver Skin Gut