Abstract
Various studies have shown that major histocompatibility complex class I-restricted cytotoxic T lymphocytes (CTL) can be isolated from lymph nodes draining sites of cutaneous infection with herpes simplex virus type 1 (HSV-1). Invariably, detection of this cytolytic activity appeared to require some level of in vitro culture of the isolated lymph node cells, usually for 3 days, in the absence of exogenous viral antigen. This in vitro "resting" period was thought to represent the phase during which committed CD8(+) T cells become "armed" killers after leaving the lymph nodes and prior to their entry into infected tissue as effector CTL. In this study we reexamined the issue of CTL appearance in the HSV-1 immune response and found that cytolytic activity can be isolated directly from draining lymph nodes, although at levels considerably below those found after in vitro culture. By using T-cell receptor elements that represent effective markers for class I-restricted T cells specific for an immunodominant glycoprotein B (gB) determinant from HSV-1, we show that the increase in cytotoxicity apparent after in vitro culture closely mirrors the expansion of gB-specific CTL during the same period. Taken together, our results suggest that HSV-1-specific CTL priming does not appear to require any level of cytolytic machinery arming outside the lymph node compartment despite the absence of any detectable infection within that site.