Low responsiveness to Dk or Db plus vaccinia virus or to Kk plus lymphocytic choriomeningitis virus assessed by availability of D or K products.

The possibility was examined that K or D regulated responsiveness of virus specific cytotoxic T cells was due to the virus-specific and differential effects on expression and/or accessibility of H-2K or D products on virus-infected target cells. Cells from established lines of fibroblasts kept in tissue culture, uninfected, infected with either vaccinia virus, with lymphocytic choriomeningitis virus (LCMV) or with both LCMV plus vaccinia virus, were compared with respect to expression of Kk, Dk and Db. H-2K or D expression was assessed by: 1) absorption of defined anti-K or anti-D antisera: 2) susceptibility to alloreactive cytotoxic T cells; and 3) susceptibility to K or D restricted virus-specific cytotoxic T cells. In all 3 tests, no virus-specific effect on Kk, Dk or Db expression on all target cells (uninfected, LCMV, or vaccinia virus infected, or doubly infected) was noticed. Most importantly, H-2k target cells infected with both LCMV plus vaccinia virus, that were not lysed by low-responder Dk-restricted vaccinia specific T cells were lysed by high-responder Dk restricted LCMV-immune T cells; in contrast, these targets were lysed by Kk-restricted vaccinia specific T cells but only poorly by Kk-restricted LCMV-immune T cells. Thus, expression or accessibility of Dk could not have limited responsiveness to vaccinia virus on this target cell since Dk was accessible to Dk-restricted LCMV-specific T cells; a similar argument can be made for the accessibility of Kk. These experiments suggest that expression and/or accessibility of Kk, Dk or Db on target cells does not explain the virus- and K or D dependent responsiveness differences of virus-specific effector T cells.