This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cells and Tissues of Immune System, Subject name: Pathology
[{'content': 'HLA-I is present on - \nSelect and explain. \nA. All nucleated cells, B. Only on cells of immune system, C. Only on B-cells, D. Only on T-cells', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., All nucleated cells o HLA-I - On surface of all nucleated cells and platelets,o HLA -II - Only on cells of immune system.o HLA complex consists of three separate clusters of genes :HLA Complex Class IClass IIClass IIIo Comprising A, B and C locio 'D' region - DR, DQ, DPComplement region encodeso Responsible foro Responsible foro C2 & C4* Graft rejection# Graft versus host responseo Properdin factor B* Cell mediated cytolysis# Mixed leucocyte reactiono Heat shock proteino Found on the surface ofo Found only on cellso TNF -a and ball nucleated cells andof the immune system platelets", 'role': 'assistant'}]