Effect of oral administration of a variety of bacteria on depressed macrophage functions in tumour-bearing rats.

In consideration of the well documented influence of normal microbial flora on the level of activation of macrophages, we evaluated the effects of oral administration of bacteria on rats with depressed macrophage functions. An oral, killed polyvalent vaccine (Diplococcus pneumoniae types I, II and III, Streptococcus haemolyticus, Staphylococcus aureus and Haemophilus influenzae), the live lyophilized Streptococcus faecium and spores of Bacillus subtilis, respectively, were administered orally to immuno-depressed rats. Results demonstrate the restoration of phagocytosis, intracellular killing and the chemotactic activity of macrophages. These experimental observations suggest that bacterial flora associated with mucosae can influence the level of activation of peritoneal macrophages.