Granulocyte-macrophage colony-stimulating factor enhances the production of eosinophil chemotactic lymphokine by egg-associated granulomas of Schistosoma japonicum-infected mice.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) produced by splenic lymphocytes obtained from Schistosoma japonicum-infected mice was partially purified by a combination of DEAE anion-exchange chromatography, concanavalin A-Sepharose affinity chromatography, and high-pressure liquid chromatography. When this partially purified GM-CSF was added to the culture of isolated intact granulomas, eosinophil chemotactic factor (ECF) lymphokine production by granulomas was significantly enhanced. The partially purified GM-CSF also enhanced ECF lymphokine production by granuloma T cells cocultured with syngeneic macrophages and specific antigen. The partially purified GM-CSF itself had neither ECF activity nor a synergistic effect with ECF lymphokine. When normal splenic macrophages were preincubated with the partially purified GM-CSF, they potentiated the ECF production by granuloma T cells under the presence of specific antigen. Augmentation of ECF lymphokine production by partially purified GM-CSF was further confirmed by using T-cell clones that were established from granuloma T cells. These results suggest that T-cell-derived GM-CSF primarily activate macrophages so that these activated macrophages can cooperate more effectively with T lymphocytes to produce ECF. Such potentiation of macrophage-T-cell interaction by GM-CSF may be important in the mechanisms of granuloma formation during an acute stage of schistosomiasis.