CD8 lymphocyte subpopulations in Peyer's patches induced by reovirus serotype 1 infection

CD8 lymphocyte population heterogeneity has been examined by using reovirus serotype 1, strain Lang (reovirus 1/L) as a model infection. We have previously reported that gut mucosal infection with reovirus stimulates the appearance of virus-specific cytotoxic T cell precursors (pCTL) in Peyer's patches (PP). The effectors that mediate reovirus-specific cytotoxicity were found to express both the Thy-1 and CD8 Ag and were MHC-restricted in their recognition of reovirus Ag. To further characterize the virus-specific precursor and effector cells we have analyzed PP cells for the expression of a novel surface Ag (termed germinal center and T cell Ag (GCT)) found on germinal center B cells and a subpopulation of CD8+ T cells. Gut mucosal infection with reovirus 1/L is capable of increasing the proportion of GCT+ CD8+ T cells in PP. Positive selection as well as depletion of GCT+ cells has demonstrated that pCTL can express this Ag, and depletion experiments have demonstrated that effector CTL express the GCT Ag. Thus, a subpopulation of GCT+ cells have been identified as Ag-specific precursor and effector CTL. These observations indicate that the expression of the GCT Ag may provide a means to identify recently stimulated pCTL or effector CTL in gut mucosal tissues.