Defects in interleukin-2 stimulation of neonatal natural killer cytotoxicity to herpes simplex virus-infected cells

Natural killer cytotoxicity (NKC) is an important early defense mechanism in viral infections. We determined the ability of interleukin-2 (IL-2), an NKC stimulator, to enhance defective neonatal NKC to virus-infected cells. Human recombinant IL-2-stimulated adult and cord blood NKC to herpes simplex virus-infected cells in a time-dependent and dose-dependent fashion. The highest level of neonatal IL-2-stimulated cytotoxicity approached the level of unstimulated cytotoxicity when adult cells are used. Single-cell experiments suggested that the cord blood defect was due not to decreased adherence but to lysis or recycling defects. IL-2 stimulated adhesion in the presence of antibody but had no stimulatory effect on antibody-dependent cellular cytotoxicity. The relative defects in IL-2 stimulation of neonatal NKC suggest that its lone use as a therapeutic or protective agent against herpes simplex virus infections is unlikely to be successful, and may require concomitant adult cells if NKC is a critical mechanism.