Immunoregulation and immunostimulation of murine lymphocytes by recombinant human interleukin-2

We report that recombinant human interleukin-2 (rhIL-2) can support the growth of murine IL-2-dependent cytotoxic T lymphocyte cell lines, augment mouse natural killer (NK) cell activity in vitro, and, as a sole stimulus, induce and maintain the proliferation of mouse lymphocytes. rhIL-2 also augmented mouse allogeneic mixed lymphocyte response and enhanced the development of alloreactive cytotoxic T cells in vitro. The intraperitoneal injection of rhIL-2 augmented peritoneal NK cell activity, whereas splenic NK cell augmentation required significantly higher levels of rIL-2. Thus, rhIL-2 is able to augment both NK cell activity in vitro and in vivo and T cell activity in vitro. These results suggest that rhIL-2 has clinical therapeutic potential since it is able to induce multiple lymphocyte functions and activities. Because rhIL-2 is highly effective for mouse cells, preclinical model systems can be readily developed that will allow us to explore the conditions needed for optimal therapeutic efficacy. Owing to the lymphocyte stimulatory nature of the rhIL-2, the monitoring of hemopoietic and leukocyte parameters during clinical rhIL-2 trials will be critical.