This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
Graft Versus host reaction is mediated by 
Select and explain. 
A. Macrophages, B. T lymphocytes, C. B lymphocytes, D. T lymphocytes and macrophages
B: T lymphocytes
Answer: B: T lymphocytes 
Explanation: In GVHD, the donated bone marrow or peripheral blood stem cells view the recipient's body as foreign. The donated T cells present in the graft, attack the tissues of the transplant recipient after perceiving host tissues as antigenically foreign. There are two forms of GVHD: Acute graft versus host disease (aGvHD). Chronic graft versus host disease (cGvHD). Ref: Ananthanarayana textbook of Microbiology 9th edition Pgno : 186