Shirahata T, Shimoi A, Kanda H, Goto H, Nakane A
Department of Veterinary Microbiology, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido, Japan.
J Vet Med Sci. 1994 Apr;56(2):293-7. doi: 10.1292/jvms.56.293.
Treatment of mice with heat-killed Propionibacterium (P.) acnes conferred transient protection against Toxoplasma infection. To investigate the mechanism of this nonspecific resistance, the production of gamma interferon (IFN-gamma) by P. acnes-injected mice was evaluated in comparison with that by noninjected controls upon infection with Toxoplasma. Mice pretreated with this bacterium produced significantly more IFN-gamma than that produced by control mice up to 24 hr of infection. A single injection of anti-IFN-gamma MAb on day 0 but not later than day 3 of infection resulted in a total abrogation of the resistance conferred by P. acnes. Likewise, daily injection of cyclosporin A (Cs-A), a potent inhibitor of T cell function, during the first 3 days of Toxoplasma infection severely exacerbated the infection, in accordance with a marked suppression of the early IFN-gamma production. In contrast, the administration of Cs-A for 3 consecutive days starting at day 4 had no significant consequence on P. acnes-induced anti-toxoplasma resistance, while it reduced greatly the ability of P. acnes-injected mice to produce IFN-gamma in the later phase of infection. Moreover, no significant increase in mortality and suppression of IFN-gamma production was noted in mice receiving anti-asialo GM1 antibody. These results suggest that the early IFN-gamma production by T cells is an essential event for the establishment of P. acnes-induced anti-toxoplasma resistance in mice.
用热灭活痤疮丙酸杆菌处理小鼠可使其获得针对弓形虫感染的短暂保护。为了研究这种非特异性抗性的机制，在感染弓形虫后，评估了注射痤疮丙酸杆菌的小鼠与未注射的对照小鼠相比γ干扰素（IFN-γ）的产生情况。用这种细菌预处理的小鼠在感染后24小时内产生的IFN-γ明显多于对照小鼠。在感染第0天但不迟于第3天单次注射抗IFN-γ单克隆抗体导致痤疮丙酸杆菌所赋予的抗性完全丧失。同样，在弓形虫感染的前3天每天注射环孢素A（Cs-A），一种强效的T细胞功能抑制剂，会严重加剧感染，这与早期IFN-γ产生的显著抑制一致。相反，从第4天开始连续3天给予Cs-A对痤疮丙酸杆菌诱导的抗弓形虫抗性没有显著影响，而它大大降低了注射痤疮丙酸杆菌的小鼠在感染后期产生IFN-γ的能力。此外，接受抗去唾液酸GM1抗体的小鼠死亡率没有显著增加，IFN-γ产生也没有受到抑制。这些结果表明，T细胞早期产生IFN-γ是小鼠建立痤疮丙酸杆菌诱导的抗弓形虫抗性的关键事件。
