This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General pathology, Subject name: Pathology
MHC restriction is a pa of all except- 
Select and explain. 
A. Antiviral cytotoxic T cell, B. Antibacterial helper T cell\/cytotoxic cells, C. Allograft rejection, D. Autoirnmune disorder
C: Allograft rejection
Answer: C: Allograft rejection 
Explanation: Reference :Robbins basic pathology 9th edition pg 149:Directrecognition.HostTcellsdirectlyrecognizetheallo- geneic (foreign) MHC molecules that are expressed on graft cells. Direct recognition of foreign MHC seems to violate the rule of MHC restriction, which states that in every individual, all of the T cells are educated to recog- nize foreign antigens displayed by only that individual's MHC molecules.