Effect of lymphokine on the activation and Fc receptor expression of rat macrophages

Lymphocyte supernatant (LS) containing lymphokine (LK) activated rat peritoneal macrophages (PM) and at the same time enhanced their Fc receptor (FcR) activity. The signs of the early activation could not be observed on alveolar macrophages (AM) but the augmented FcR expression occurred under the effect of lymphokine. The LK-induced macrophage activation and the enhancement of erythrocyte—antibody (EA) rosette formation were found to be independent of each other. In the presence of soybean trypsin inhibitor (STI) the crude lymphokine-induced augmented EA rosette formation was only slightly diminished. However, it did not seem likely that the LK components of molecular weight over 15,000 could enhance the number of rosettes under the effect of protease inhibitor.These data indicate that the macrophage proteases play an important role in the generation of EA rosette formation enhancing breakbown product(s) during the macrophage—lymphokine interaction.