IMUVERT ACTIVATION OF NATURAL-KILLER CYTOTOXICITY AND INTERFERON-GAMMA PRODUCTION VIA CD16 TRIGGERING

The effect and mechanism of action of Imu Vert, a new biological response modifier consisting of ribosomes and natural membrane vesicles of Serratia marcescens, on endogenous natural killer (NK) cells and activated NK activity has been analyzed. The studies showed that endogenous NK activity of peripheral blood mononuclear cells (PBMC) from normal cell donors was signicantly increased (P<0.03) against K562, U937, and Molt-4 target cells. PBMC from cord blood of newborn infants lacking NK activity were upregulated (1.5-4 fold over endogenous NK activity) by Imu Vert. Other studies showed that the abnormal NK activity of PBMC from patients with the human immunodeficiency virus (HIV) infection was significantly augmented in vitro (P<0.01) by Imu Vert. Imu Vert strongly stimulated interferon gamma production and in combination with interleukin 2 produced synergistically enhanced interferon gamma production and greater cytotoxicity than that induced by either alone. Studies on lymphocyte differentiation antigen expression following treatment with Imu Vert indicated that Imu Vert triggers interferon gamma production through binding the low affinity IgG Fc receptor, type III, CD16. The studies suggest that Imu Vert may trigger interferon gamma production by binding to the Fc receptor and that the amplitude of the ensuiing reaction and the ability of Imu Vert to induce cytotoxicity in a setting where this activity has been down regulated is based on the absence of suppressor activation or direct contra suppressor activity. © 1990.