Cell mediated immunity in experimental influenza and parainfluenza infection.

Cell mediated immunity (CMI) to Sendai and Kunz viruses, determined by a 51Cr release assay of cytotoxicity, has been shown to develop during the course of these infections. This virus specific response is mediated by sensitised T cells, and takes place against a background of innate cell mediated immunity. The mediator of this innate cytotoxicity exhibits none of the characteristics of T, B or K cells, but bears close resemblance to the NK cell which is spontaneously cytotoxic for certain tumour cells. Removal of the virus specific CMI by T cell depletion produces a moderate immunosuppressive effect. The nature of this effect and the role of CMI in these infections are discussed.