Mouse spleen cell-derived toxoplasma growth inhibitory factor: its separation from macrophage migration inhibitory factor.

Spleen cells from hyperimmunized mice infected with Toxoplasma gondii were cultured in vitro with Toxoplasma specific antigen. The supernatant produced from the cells were termed lymphokines (LKs). The LKs were divided into 4 major fractions, namely: LKs-I, LKs-II, LKs-III and LKs-IV, according to the elution pattern on Sephadex G-100 gel columns. Partially purified LKs contained 2 MIF peaks, namely: MIF-I in LKs-II fraction and MIF-II in LKs-IV fraction. In this study, Toxoplasma growth inhibitory factor (Toxo-GIF), which inhibits the multiplication of Toxoplasma within non-immune macrophages in vitro, was separated by the same method as MIF separation, i.e. Sephadex G-100 gel filtration. Toxo-GIF activity was present in the LKs-II fraction in which MIF-I was also detected with a calculated molecular weight of 30,000 to 40,000. This murine LKs inhibited Toxoplasma multiplication only in murine macrophages but not in guinea pig macrophages or canine monocytes. Cytotoxic substances against macrophages were observed in the LKs-IV fraction, however, no Toxo-GIF was present in this fraction which in addition contained MIF-II with a calculated molecular weight of 3,000 to 5,000.