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: Microbiology
[{'content': 'Hyperacute rejection occurs most commonly in which organ: March 2007 \nSelect and explain. \nA. Liver, B. Kidney, C. Lung, D. Hea', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. B: Kidney Hyperacute rejection is a complement-mediated response in recipients with pre-existing antibodies to the donor (for example, ABO blood type antibodies). Hyperacute rejection occurs within minutes and the transplant must be immediately removed to prevent a severe systemic inflammatory response. Rapid agglutination of the blood occurs. This is a paicular risk in kidney transplants, and so a prospective cytotoxic crossmatch is performed prior to kidney transplantation to ensure that antibodies to the donor are not present. Hyperacute rejection is analogous to a blood transfusion reaction as it is a humoral-mediated immune response. For other organs, hyperacute rejection is prevented by transplanting only ABO-compatible grafts. Hyperacute rejection is not significant in liver allografts and cellular transplants because these tissues have remarkable regenerative abilities. Hyperacute rejection is the outcome of xenotransplanted organ in non-immunosuppressed recipients', 'role': 'assistant'}]