9. As shown in the figure, a mouse, the offspring of a MHCk father and MHCd moth
ID: 209291 • Letter: 9
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9. As shown in the figure, a mouse, the offspring of a MHCk father and MHCd mother, was infected with the LCM virus. After several days to allow an immune response to occur, spleen cells were harvested from the mouse and mixed with four different Cr -labeled target cells (indicated as 1-4 in figure). For each target population 1-3, the results are shown--the target cells were lysed or not lysed. (10 pts) a. For each of the 3 different targets (1-3), explain the reason for the result obtained. For each, answer with the following format, "Target cells 1 were not lysed because..."; "Target cells 2 were lysed because..."; Target cells 3 were not lysed because..." Explain the basis for your b. For target cells 4, predict whether these cells are lysed or not. prediction c. Predict whether the MHCk target cells (ike in case 2) would have been lysed if they been infected with herpes simplex virus, instead of LCM virus. Briefly explain your reasoning LCM virus MHCkx d Spleen cells (containing Te cells) Cr MHCK target cells MHCk LCM-infected MHCb LCM-infected MHCdLCM infected target cells target cells target cells 4 Targets Not Lysed Targets Lysed Targets Not Lysec TargetsExplanation / Answer
Cytotoxic T cells ability starts with two criteria 1. Self MHC 2 . Foreign peptide. These two are essential for starting of activity of cytotoxic T cells. In other word cytotoxic T cell only destroyed those cells which have a foreign peptide processed by self MHC molecules. If no foreign peptide is present it will not lysed, if it is not self MHC it will not lysed.
So target cell 1 is not lysed because there is no foreign peptide. Tc cell recognize MHC k target cell as self MHC so lysis is not occured.
Target cell 2 is lysed because cytotoxic T cells get foreign peptide ( virus particle) processed with MHCk cells ( self ).
Target cell 3 is not lysed because cytotoxic T cells did not get self MHC. As it is processed by MHCb that is foreign MHC to cytotoxic T cells , it is not lysed.
Target cell 4 will lysed because MHCd also a self MHC because progeny had a parents with MHC d. So again MHC d will process antigen and shows to Tc cells and it will be lysed
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