Demonstration of MHC class II-restricted cytotoxic T lymphocytes in mice against herpes simplex virus.

In humans CD4+ major histocompatibility complex (MHC) class II-restricted T cells dominate cytotoxic T-lymphocyte (CTL) responses to herpes simplex virus (HSV), whereas in the mouse only CD8+ MHC class I-restricted CTL have been reported. In this study, we demonstrate that a minor fraction (around 30%) of the response in draining lymph nodes of acute local HSV infections is attributable to CD4+ CTL mice. Such CTL were identified on the basis of antiserum inhibition studies, negative depletion approaches, as well as their differing antigen processing requirements to CD8+ MHC class I-restricted CTL. A possible role for CD4+ CTL as immunoregulators in local infections is discussed briefly.