Natural killer cell cytotoxicity to herpes simplex virus-1-infected cells is not altered by pregnancy.

There is evidence to suggest a decrease in natural killer cell cytotoxicity during pregnancy, but information regarding immune responsiveness to actual infection is limited. An in vitro study was undertaken to examine the effect of herpes simplex virus infection on natural killer cell cytotoxicity with peripheral blood mononuclear cells from pregnant (N = 8) and nonpregnant (N = 5) women. The peripheral blood mononuclear cells were separated by Ficoll-Hypaque centrifugation. Effector cells were incubated with live herpes simplex virus-1, ultraviolet-inactivated herpes simplex virus-1, or media alone for 18 hours at 37 degrees C. K562 target cells were used in a sodium chromate release assay with an effector-to-target cell ratio of 100:1. Baseline natural killer cell values (mean +/- SE) for pregnant patients (13.4% +/- 2.4%) and nonpregnant patients (19.8% +/- 3.7%) were similar. Natural killer cell cytotoxicity was significantly increased by incubation with live virus for both pregnant (37.5% +/- 6.2%) and nonpregnant subjects (49.8% +/- 7.6%). There was no difference in mean values between media and ultraviolet-inactivated herpes simplex virus-1-exposed samples for either group. Results suggest that (1) infection with live virus, but not viral antigen alone, can augment natural killer cell response in vitro and (2) natural killer cell response to herpes simplex virus-1 infection is not altered by pregnancy.