Phagocytosis-enhancing effect of human leukocyte interferon preparation of human peripheral monocytes in vitro.

It was found that the phagocytosis of human peripheral monocytes was enhanced by human leukocyte interferon preparations. This activity showed species-specificity and a positive correlation between interferon titer and phagocytic activity. When human monocytes were treated by interferon, the pahagocytic activity was enhanced. But when interferon was added to the latex, the enhancement was not observed. The interferon preparation did not only increase the number of phagocytic cells, but also enhanced the degree of phagocytosis in individual cells. The factor responsible for the enhancing effect was inactivated by trypsin, but was not inhibited by actinomycin D.