The proliferation of splenocytes from health adults was induced by anti-CD₃ McAb and IL-2. The proliferative potential of the splenocytes and antitumor activity of their culture supernatants of splenocytes were studied. The results showed that anti-CD₃ McAb not only enhanced the proliferation of the splenocytes directly, but also enhanced that of induced by IL-2. Their enhancing effect was more significant when the incubation time in vitro was prolonged. The culture supernatants of anti-CD₃ and IL-2 induced splenocytes also had the antitumor activity and enhancing capability to the antitumor activity of LAK cells. The results suggested that LAK cells could secret lymphokine, and this effect would be synergically promoted when anti-CD₃ and IL-2 were simultaneously used.