In vitro enhancement of natural killer cell activity against herpesvirus-infected targets in patients with acute lymphocytic leukemia.

The present study was carried out to determine whether natural killer (NK) activity against virus-infected target cells could be enhanced in peripheral blood lymphocytes (PBL) taken from patients with acute lymphocytic leukemia. Nonspecific cell-mediated killing of heterologous herpesvirus-infected B lymphoblastoid targets could be enhanced by pretreating PBL with interferons-alpha or -gamma, or with interleukin-2. NK activity was substantially enhanced over that of untreated cells, and virtually all cytolytic activity was attributable to CD16+ NK cells. Pretreatment of PBL with a combination of cytokines resulted in additive, but never synergistic enhancement of NK activity. The results suggest that cytokine therapy may provide a useful means for treating severe varicella zoster infections in immunocompromised children.