Recovery of hemopoiesis in lethally irradiated mice after treatment with propionibacteria.

Three investigated strains of propionibacteria (P. acnes, P. granulosum and P. avidum) injected intraperitoneally in doses of 1.5 mg per mouse, significantly prolonged survival of lethally (8.50 R) irradiated mice. P. granulosum, being the most effective in increasing survival of irradiated mice was chosen for the studies on the activity of bone-marrow pluripotent stem cells. The number of endogenous spleen colonies was significantly increased in mice injected with P. granulosum 3 days prior to or 4 hours after irradiation with 650 R. However, injection of P. granulosum to donors prior to bone-marrow transplantation significantly decreased the number of exogenous spleen colonies in recipients irradiated with 850 R. These results, together with the observed increase in number of CFU-S in peripheral blood and elevated relative spleen weight after injection of P. granulosum, suggest that propionibacteria stimulate migration of CFU-S from bone-marrow via peripheral blood into spleen. Stimulation of CFU-S proliferation and differentiation is also taken into account.