Defect of macrophage function in the antibody response to sheep erythrocytes in systemic Mycobacterium lepraemurium infection

Abstract

THE need for macrophages for optimal antibody responses, both in vivo and in vitro, to certain antigens is now established^1,2 and this paper describes experiments which have used this requirement to demonstrate a deficiency of macrophage function in mice experimentally infected with the rodent leprosy bacillus, Mycobacterium lepraemurium. This organism is an obligate intracellular dweller and is found particularly inside cells of the macrophage series although in terminal infection other cell types may be invaded. Systemically infected mice characteristically show macrophages overloaded with bacilli, ever increasing numbers of granulomata and increasing spleno- and hepatomegaly³. There is an increase in the phagocytic activity of the spleen and liver at an early stage of infection (I.N.B. and V.S.Š., in preparation) indicative of alterations in macrophage function and we report here experiments which show that the in vivo and in vitro antibody response to sheep erythrocytes (SRBC) is depressed at later stages of infection. The results indicate a defect of macrophage function.