Effects of Bacterial Immunopotentiators, LC 9018 and OK-432, on the Resistance Against Mycobacterium intracellulare Infection in Mice

Bacterial immunopoteniators, Lactobacillus casei YIT 9018 (LC 9018) and penicillin G-treated Streptococcus pyogenes (OK-432), were examined for their effects on the host resistance against Mycobacterium intracellulare infection in mice. When these agents were given intraperitoneally (i. p.) to mice, most of the administration protocols used in the present study failed to show a significant protective or therapeutic effect against the infection. Moreover these bacterial preparations could not exhibit a synergistic effect with minocycline in vivo. With a frequent i. p. administration of these agents, there was a tendency toward suppression of the host defense mechanisms to the infection, presumably by induction of some types of suppressor cells. Thus, it is likely that for an expression of more marked protective and/or therapeutic effects of these immunopotentiators against M intracellulare infection, the administration by routes other than i. p. is preferred.