Influence of propionibacterium avidum KP-40 on the proliferation, maturation, emigration and activity of thymocytes and monocytes.

Inactivated cells of Propionibacterium avidum KP-40 could be shown to induce thymocyte proliferation and maturation in BALB/c-mice after intraperitoneal administration of the optimal immunomodulating dosage (1 mg per mouse). The increase in thymus weight and thymocyte numbers per mg organ weight was most pronounced and statistically significant 10 days after P. avidum KP-40 administration. Determinations of lymphatic subsets revealed a considerable up-regulation of mature cells expressing helper/inducer (L3T4+) or cytotoxic/suppressor (Lyt-2+) phenotypes and immature cells presenting both L3T4+/Lyt-2+ antigens. Obviously, P. avidum KP-40 administration accelerated murine thymocyte proliferation and maturation. Counts of BALB/c-mouse peripheral blood lymphocytes (PBL) and monocytes (PBM) revealed statistically significant increases after P. avidum KP-40 administration with peak values after 6-10 days. The determination of activated PBL (expressing interleukin-2 receptors) or PBM (expressing MAC-3 antigens) proved that P. avidum KP-40 induced a potent immunostimulation since counts of these cells were significantly enhanced after P. avidum KP-40 treatment.