Human neonatal leukocyte interferon production and natural killer cytotoxicity in response to herpes simplex virus

Human neonates are susceptible to severe herpes simplex virus (HSV) infection; however, the immunologic mechanisms explaining this lack of resistance remain to be defined. The ability of leukocytes from adults and neonates to produce interferon (IFN) in response to HSV challenge and to destroy HSV infected cells in the absence of antibody, termed natural killer cytotoxicity (NKC), were compared. The NKC activity of leukocytes from neonates (13.5 +/- 2.5%) was significantly lower (p less than 0.005, Mann Whitney test; p = 0.007, Students t-test) than the NKC activity of adult leukocytes (25.7 +/- 3.2%). In contrast, no significant difference was observed between IFN production by neonate (87.7 +/- 29.1 units) and adult (87.8 +/- 29.4 units) leukocytes.