DIFFERENTIAL ANTIGEN RECOGNITION BY T-CELLS FROM THE SPLEEN AND CENTRAL-NERVOUS-SYSTEM OF CORONAVIRUS-INFECTED MICE

CD8(+) cytotoxic T lymphocytes (CTLs) isolated from the central nervou s system (CNS) of C57Bl/6 mice acutely infected with mouse hepatitis v irus, strain JHM (MHV-JHM), and analyzed in a direct ex vivo cytotoxic ity assay recognize two epitopes (H-2D(b)- and H-2K(b)-restricted enco mpassing amino acids 510-518 and 598-605, respectively) within the sur face (S) glycoprotein. In contrast, CD8(+) T cells isolated from the s pleens of mice inoculated intraperitoneally with MHV-JHM and restimula ted in vitro only respond to the H-2D(b)-restricted epitope. In this r eport, the preferential recognition of the H-2D(b)-restricted epitope is confirmed using splenocytes stimulated in vitro with either MHV-JHM -infected MC57 cells or with a cell line expressing the S protein and analyzed in secondary CTL assays. To determine whether these results r epresent a difference in epitope recognition between the spleen and CN S, secondary CTL assays were performed using spleen cells coated with peptides encompassing the CTL epitopes as stimulators. Under these con ditions, both epitopes sensitized cells for lysis by spleen-derived CT Ls, suggesting that both epitopes were recognized by splenic CD8(+) T cells after infection in vivo. Furthermore, limiting dilution analysis indicated that the precursor frequency of splenic CD8(+) T cells spec ific for both the H-2K(b)- and H-2D(b)-restricted epitopes were not si gnificantly different. Thus, the results suggest that in vitro stimula tion of splenocytes specific for the H-2K(b)-restricted epitope is ine fficient after endogenous processing but that this inefficiency can be corrected if peptide is provided exogenously at sufficiently high con centrations. As a consequence, the results also show that cells respon sive to both of the previously identified CNS-derived CD8(+) T cell ep itopes are present in the infected spleen at nearly the same frequency . (C) 1996 Academic Press, Inc.