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
[{'content': 'The HLA class III region genes are important elements in \nSelect and explain. \nA. Transplant rejection phenomenon, B. Antigen presentation and elimination, C. Immune surveillance, D. Governing susceptibility to autoimmune diseases', 'role': 'user'}, {'content': 'Answer: D \nExplanation: *HLA class III region contains genes for early complement components C2 and C4 of classical pathway.\n*Deficiency of these early components of the classical pathway viz C1, C2 and C4 is associated with autoimmune diseases like SLE and other collagen vascular diseases.\n• These genes are thus, important in regulating susceptibility to autoimmune disease\n• Class III genes do not participate in MHC restriction or graft rejection components.', 'role': 'assistant'}]