This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunity, Subject name: Pathology
Graft vs Host reaction can be reduced by? 
Select and explain. 
A. Irradiation, B. Leuckoreduction/leuckofiltration, C. Immunosuppression, D. Buffy coat removal
A: Irradiation
Answer: A: Irradiation 
Explanation: Ans. (a) Irradiation(Ref: Wintrobes 13th/704-705)Irradiation with a dose of 2,500 cGy at the center of the irradiation field, with a minimum dose of 1,500 cGy at any point in the field inhibits proliferation of donor lymphocytes but has no significant adverse effect on red cell, platelet, or granulocyte function.It should be noted that though the other options are also effectice in reducing the leukocytes but they do not completely deplete the lymphocytes and so can cause GVHD.