STUDIES ON THE EFFECTS OF PHAGOCYTIC STIMULATION ON MICROBIAL DISEASE: V. STIMULATION OF PHAGOCYTIC ACTIVITY OF MONOCYTES AGAINST TUBERCLE BACILLI, STRAIN BCG

Abstract

Monocytes were obtained by the washing of the peritoneal cavity of guinea pigs with Hanks' solution six days after intraperitoneal administration of a saline solution containing glycogen. Phagocytosis of tubercle bacilli (BCG strain) was studied after a one hour incubation at 37 °C. under the influence of histamine and 1,4-dimethyl-7-isopropyl-bicyclo-decapentane, which latter substance had shown a beneficial influence on the outcome of experimental tuberculosis. Histamine increased the phagocytic activity of monocytes, within the limits of 1 μgm. to 10 μgm per ml. This stimulation was inhibited in vitro by a synthetic antihistamine substance. Fifty and 100 μgm. per ml. histamine decreased the phagocytosis of tubercle bacilli (BCG) by the monocytes. Monocytes withdrawn from histamine treated guinea pigs showed no stimulated activity. From 0.5 to 100 μgm. per ml. of 1,4-dimethyl-7-isopropylbicyclo-decapentane stimulated the phagocytic activity of monocytes against tubercle bacilli (BCG) in vitro and monocytes withdrawn from animals treated with the same substance showed equally a stimulated activity. This increased phagocytosis was equally inhibited in vitro by the antihistamine, but to a lesser degree than the inhibition of the histamine stimulated phagocytosis. The above observations suggest that the stimulating action of the 1,4-dimethyl-7-isopropyl-bicyclo-decapentane is a direct action on the monocytes rather than an indirect one caused by activation of latent histamine. Experiments also show the possibility of stimulation of the cellular defense mechanism, by appropriate treatment.