ABSTRACT
The usual functional inhibition of medium-cultured monocytes by Lymphokine-activated killer (LAK) cells was reversed when the monocytes were cultured in IFN-g. Thus, the opposing effect of granulocyte macrophage-colony stimulating factor (GM-CSF) and IFN-g on monocyte functional susceptibility was similar to that found earlier on monocyte lysis by LAK cells. Antigen presentation is a sentinel process in the immune system. Monocytes take up antigen, process it and display an immunogenic fragment to lymphocytes, thereby delivering an activation signal to T cells. IFN-g protected monocytes from LAK suppression of antigen presentation. The opposing effects of GM-CSF and IFN-g on monocyte functional susceptibility, as measured by antigen presentation, were equivalent to those seen on monocyte antifungal activity. IFN-g protected monocytes from LAK suppression of antigen presentation. Monocytes are important accessory cells in the activation of T cells for specific antigen recognition and for control of microbial invasion.
