Stimulation of prostaglandin formation by an antigen- and Ia-restricted T-cell-macrophage interaction.

Stimulation of macrophages by zymosan phagocytosis triggers the respiratory burst and induces an early release of lysosomal hydrolases and E-type prostaglandins (PGE). We have studied whether antigen presentation by macrophages to helper T-cells elicits a comparable sequence of events. Cloned T-helper cells specific for hen egg albumin (EA) were added to histocompatible or histoincompatible resident mouse peritoneal macrophages in the presence of EA or an unrelated antigen, and the changes in biochemical parameters were monitored. The interaction between macrophages. T-helper cells and EA induced the production of PGE, but no release of lysosomal hydrolases or activation of the respiratory burst. In addition T-cell proliferation was observed. By contrast, no proliferation and no biochemical changes were observed when histoincompatible macrophages or unrelated antigen were used. When the experiments were done in the presence of indomethacin to inhibit PGE release, T-cell proliferation was enhanced. These results suggest that the PGE released may exert a feed-back control of the T-cell response.