Activation of monocytes in vitro to produce lymphocyte dysfunctions

Abstract

Model experiments have been conducted to test whether activation of monocytes in vitro causes the same types of immune dysfunctions of lymphocytes that are observed after patients receive radiation therapy. These tests were performed since there is evidence that the immunosuppression following irradiation is caused partly by activated monocytes. It was observed that lipopolysaccharide (LPS) from Escherichia coli, a potent activator of monocytes, strongly suppresses the proliferative responses of lymphocytes to purified protein derivative of tuberculin and in the mixed lymphocyte culture provided monocytes are present in the cultures. LPS had little or no effect on the phytohemagglutinin and poke weed mitogen responses of lymphocytes regardless of the presence of monocytes. It is concluded that activated monocytes depress lymphocyte functions in a fashion similar to that of radiation therapy.