Murine peritoneal macrophages, human fibroblasts and human ovarian teratocarcinoma cells were treated with CDDP (10 micrograms/ml) and "poly-plat" (10 micrograms/ml) for 2 h and cultured for 2-96 h. After "poly-plat" treatment macrophages developed cytoplasmic extensions much faster and secreted higher levels of interleukin-2 (IL-2), compared to CDDP. "Poly-plat" treated human fibroblasts demonstrated a significant release of IL-2 (138 pg/ml), compared to CDDP (64 pg/ml) or the untreated normal cells (31 pg/ml) after 8 h. Correspondingly there was a 53% increase in cells after "poly-plat" treatment compared to only 37% after CDDP. However, human ovarian teratocarcinoma cells didn't show any significant increase in IL-2 levels after "poly-plat" treatment and there was instead a decrease of 15% in cell numbers at 8 h. Based on our studies, we propose that "poly-plat" is more effective in activation of the macrophages and human fibroblasts in terms of IL-2, but not so with human ovarian teratocarcinoma cells.