Interferon-gamma inhibits endocytosis of soluble animated beta-1,3-D-glucan and neutral red in mouse peritoneal macrophages.

We previously demonstrated that soluble animated beta-1,3-D-glucan (AG) is internalized after binding to a specific beta-glucan receptor on macrophages. Internalization, but not binding, of AG is reduced when the macrophages are treated with IFN-gamma. Because our data indicated that AG is taken up by macrophages through beta-glucan receptor-mediated endocytosis, we wanted to characterize further the inhibitory effect of IFN-gamma on endocytosis.

IFN-gamma inhibits internalization of soluble aminated beta-1,3-D-glucan by macrophages and thereby down-regulates the glucan induced release of TNF-alpha and IL-1 beta.

We have previously shown that soluble animated beta-1,3-D-glucan (AG) and glucan-derivatized microbeads (GDM) bind to the specific beta-glucan receptor on mouse peritoneal macrophages. Phagocytosis of GDM by macrophages is mediated through the beta-glucan receptor. IFN-gamma which increases macrophage phagocytic capacity, also increased the phagocytosis of GDM.

A novel immunomodulator soluble aminated beta-1,3-D-glucan: binding characteristics to mouse peritoneal macrophages.

We have previously reported that soluble aminated beta-1,3-D-glucan (AG), a potent immunomodulator, specifically inhibited binding and internalization of AG-coated microbeads (GDM) in mouse peritoneal macrophages. The present study was undertaken to determine parameters of AG binding to macrophages. For this purpose, AG was conjugated with tyraminyl cellobiose (TC), which can be radioiodinated.

Cytokines and PGE2 modulate the phagocytic function of the beta-glucan receptor in macrophages.

Under serum-free conditions the beta-glucan receptor of mouse macrophages mediates phagocytosis of beta-1,3-D-glucan-coated microbeads (diameter 2 microns). IFN-gamma increases the phagocytic function of the beta-glucan receptor in a dose-dependent manner, giving the plateau level at 100 U/ml. Maximum activity appears 9 h after addition of IFN-gamma to the cells.