Experimental infection of inbred mice with herpes simplex virus. II. Interferon production and activation of natural killer cells in the peritoneal exudate.

The peritoneal exudate cells (PEC) represent the first line of defence against the virus in the mouse model of intraperitoneal (i.p.) infection with herpes simplex virus (HSV). We have therefore studied interferon production and activation of natural killer (NK) cells in vitro in PEC of HSV-injected mice. Injection of HSV caused a marked increase in NK cell activity, as reported by others. PEC from HSV-injected mice also produced high titres of interferon. This observation may be important since induction of interferon appears to be the primary event whereas activation of NK cells - as generally accepted - represents a secondary effect of the interferon produced. The HSV-induced NK cells shared the properties of NK cells in that they were sensitive to a monoclonal anti-theta antibody and to a monoclonal anti-Qa 5 antibody. In contrast, the cells producing interferon were not sensitive to either antibody. Irradiation (200 R) of the mice 24 h before injection of the virus decreased interferon production by more than 90%. The identity of the interferon-producing cells is unknown, but they may represent B cells.