抄録
As stated in our previous reports, comparative observations were made on the develop-ment of experimental murine leprosy in various inbred strains of mice, concerning the relation between subcutaneous leproma at the inoculation site and evolution of visceral lesions. On the basis of the findings in these experiments, this author considered that mouse leprosy could be classified into two polar types, benign and malignant. In the former type which is represented by C57BL/6 and ddY strains, the subcutaneous leproma appears earlier and is small, hard and sharply defined, whereas the leproma of the latter type which is represented by C3H strain develops slower but becomes much larger and soft with a diffuse thickening appearance. In the cases of malignant type, visceral lesions developed severe with time and then extensive involvement may have a fatal out-come. On the other hand, the visceral organs of benign type revealed, in general, the presence of slight lesions even in the advanced cases.
However, it was obvious from the results of long-term observation, up to 80 weeks, that, in the cases of CF#1 mice, subcutaneous infection with murine leprosy bacilli found to give a disparity in the relation between the feature of leproma at the inoculation site and the involvement of visceral organs: i.e., subcutaneous leproma showed the benign feature but visceral lesions became severe as observed in the malignant cases.
To solve this disparity, further long-term observations, up to 80 weeks, were made in various inbred strains of mice (C3H, fm, CFW, BALB/C, KK, DDD and C57BL/6) by the same manners above described.
In strain C3H, the typical malignant course of the disease was followed throughout the observation period. The disease course of fm mice comparable to that of C3H mice. In the mice of C57BL/6 and DDD strains, subcutaneous leproma showed the benign type and remained generally small with a tendency to regress at the late stage of infection. At the end of experiment two of C57BL/6 mice were extremely emaciated and died, showing severe visceral lesions. But in the other mice of these two strains, no extensive involvements were observed in their organs.
On the contrary, in mice of KK, BALB/C and CFW strains, the feature of subcuta-neous leproma at the inoculation site was typical benign, but the development of visceral lesions was comparable to that of malignant cases.
Taking these facts into our consideration, it would be reasonable to assume that the disparity above mentioned might result from the grade of developing immunity in thehosts. And then mouse leprosy should be classified into three types, benign, intermediate and malignant. In the cases of intermediate type, newly classified, the leproma at the inoculation site shows the benign feature but the visceral lesion develops severe with time as observed in the malignant cases.
