The role of p53 in regulating antiviral T cell responses

It is now well established that viral infections can induce large expansion s of Ag-specific CD8(+) T cells. These cells divide very rapidly with an es timated doubling time of similar to6 h. When virus is cleared, the vast maj ority of these effector CD8 T cells undergo apoptosis. The remaining memory cells persist at constant levels and provide the basis for the accelerated recall response upon rechallenge. The molecular mechanisms that control th e rapid proliferation and death of Ag-specific T cells are poorly understoo d. Because of its important role in controlling cell proliferation and deat h, we examined antiviral immune responses in p53(-/-) mice using lymphocyti c choriomeningitis virus. We found that effector CD8 and CD4 responses were comparable but that memory levels were slightly higher in -/- mice compare d with +/+ mice. The lack of a major difference in virus-specific T cell re sponses between +/+ and -/- mice suggests that p53 only plays a minor role in regulating the proliferation, apoptosis, and maintenance of Ag-specific T cells. Thus, it appears that the primary function of p53 is in controllin g "illegitimate" proliferation and tumor development and not in regulating Ag-specific T cell responses.