In vitro induction of human cell-mediated cytotoxicity directed against herpes simplex virus-infected cells: characterization of the effector lymphocyte.

Normal human peripheral blood mononuclear leukocytes (PBML) were incubated (sensitized) in vitro for 6 days with herpes simplex virus type 1 (HSV-1)-infected cells. The sensitized PBML were then tested in a 5-hr 51Cr-release microassay against uninfected or HSV-1-infected target cells. PBML subpopulation-depletion studies revealed that the effector cells were neither B cells nor monocytes, but that their activity was found both in the E-rosetting and the non-E-rosetting lymphocyte fractions. Further separation techniques showed that the effector cells in either fraction expressed an Fc receptor for IgG. In vitro-generated, virus-specific cytotoxic activity thus appeared to be mediated both by a T gamma cell and a special null cell, suggesting possible NK cell involvement.