Abstract
As reported in the previous paper, during the course of investigation on mouse leprosy, this author encountered with the fact that subcutaneous nodules in hybrid mice from crosses between C57BL/6 and CF1 developed and reached to their maximum size in a comparatively early period, being followed by a marked regression. This type of mouse leprosy is same as “benign” previously designated by the author.
In the present experiment, these mice were infected subcutaneously with murine leprosy bacilli and. then superinfected subcutaneously at varying intervals after primary infection. When superinfection was made 2 weeks after primary infection, only a slight difference was noted in the size of leproma palpable at the challenged site between the two groups with and without the primary infection. However, in the cases of superinfection at 8 or 14 weeks, the development of leproma at the site of superinfection was markedly suppressed in the animals with the primary infection. These results therefore support the view that the regression in benign mouse leprosy is due to the developing immunity in those mice.
A similar tendency was observed in the subcutaneously challenged mice which had been previously infected intraperitoneally, although most of them died of severe visceral lesions caused by primary infection.
