Stimulation of the non-specific resistance by Corynebacterium parvum and Bacillus calmette Guérin.

The effect of pretreatment of intravenously administered killed Corynebacterium parvum (CP) and living BCG was studied in various model systems. Both vaccines caused an increased resistance to Listeria monocytogenes, indicating macrophage activation. Only CP exerted a suppressive effect on T-cell-mediated immunological phenomena (skin allograft survival; antibody production to tetanus toxoid; expulsion of adult T. spiralis worms from intestine). Results of experiments with congenitally athymic (nu/nu) mice and their heterozygous thymus-bearing (+/nu) littermates indicated that CP can induce macrophage activation in the absence of functional T-cells, whereas BCG-induced stimulation is a T-cell-dependent phenomenon.