Postirradiation recovery of hemopoiesis in mice treated with Propionibacterium granulosum.

The effect of Propionibacterium granulosum on spontaneous regeneration of hemopoiesis in nonlethally (250 or 400 rads) irradiated mice was investigated and measured by peripheral blood leukocyte counts each 2 days after irradiation and incorporation of 3H-thymidine into spleen and thymus in vivo. P. granulosum injected intraperitoneally in a dose of 1.5 mg per mouse, 7 days before or 4 days after irradiation, resulted in accelerated recovery of hemopoiesis after nonlethal irradiation with significantly higher leukocytosis, as compared with a control non-treated with bacteria. This was accompanied by elevated spleen and thymus weight and higher incorporation of 3 H-thymidine into spleen cells.