Adjuvanticity of lactobacilli. I. Differential effects of viable and killed bacteria

The adjuvanticity of Lactobacillus brevis and Lactobacillus plantarum was the subject of this study. The latter was the better adjuvant in both delayed hypersensivity and antibody formation to sheep red blood cells. Viable L. plantarum stimulated exclusively the delayed hypersensivity, where heat-killed bacteria had an adjuvant effect on antibody formation. For optimal adjuvant effects lactobacilli had to be injected in a dose of 10(8) into the same site as the antigen. Viable lactobacilli and to a lesser degree heat-killed bacteria induce hepato-splenomegaly, suggesting mediation of the adjuvant activity by the reticuloendothelial system. Granuloma formation with mainly mononuclear cell infiltrates could be observed after subcutaneous administration of viable lactobacilli whereas heat-killed lactobacilli induced granulomata containing about equal numbers of granulocytes and mononuclear cells. The possible clinical application of L. plantarium in the immunotherapy of tumours is suggested.