Direct activation of human adherent cells by yeast cell wall in vitro

Adherent cells from human peripheral blood could be activated by cocultivation with yeast cell wall for 3 days and the acid phosphatase activity of these cells was elevated. Lymphocyte response to phytohemagglutinin (PHA) was reduced in the presence of yeast cell wall ranging from 0.1 microgram/ml to 1000 micrograms/ml. When the activated adherent cells were added to non-adherent cells or the cells from lymphoid cell line (HD-10), derived from Hodgkin's disease, DNA synthesis of these target cells was suppressed. The supernatants from the activated adherent cells were also inhibitory to the proliferation of the cell line. It is suggested that this in vitro system is useful in investigating the mechanisms of macrophage activation and the roles of macrophages in immune responses.