Biphasic protection against bacterial infection in mice induced by vaccination of Propionibacterium acnes.

A single intraperitoneal injection of the phenol-treated cells of Propionibacterium acnes into mice showed nonspecific resistance against subsequent lethal doses of an intraperitoneal challenge of Klebsiella pneumoniae, Staphylococcus aureus, and Streptococcus pyogenes. The protection showed a biphasic pattern. The maximum protection, designated as the early phase protection, was seen in mice injected with P. acnes vaccine 1 to 2 days before the challenge, whereas the late phase protection was seen in mice vaccinated 16 to 22 days before the challenge. The activity of the reticuloendothelial system in mice after vaccination also showed a biphasic pattern with the peak on days 4 and 12. The delayed activation of the reticuloendothelial system lasted up to 3 weeks and coincided with the period of the late phase protection. The early phase resistance was markedly impaired by the treatment with hydrocortisone and carrageenan, but not by the treatment with anti-thymocyte serum, actinomycin D, or cyclophosphamide. The number of peritoneal polymorphonuclear leukocytes in vaccinated mice increased on days 1 to 2. The number of macrophages also increased at 2 to 21 days after vaccination and reached its maximum on day 14. Total activities of acid phosphatase, Nitro Blue Tetrazolium reduction, and the phagocytic activities of peritoneal exudate cells were also enhanced on and after day 1 after the injection of P. acnes vaccine.