Cytological studies on host-parasite relations in experimental leprosy of mice.

The details of different manifestation patterns of experimental leprous lesions of mice were described from the viewpoint of host vs. parasite relationship and the reticuloendothelial origin of the lepra cell. Three kinds of pretreatment, i. e., typhoid vaccine as a stimulant, Evans blue as a disturbant and cardiolipin as a depressant of the reticuloendothelial function were given to mice of dd-strain before the inoculation of lepra bacilli of Hawaiian strain. The experiments were carried out up to 15 weeks of the infection. The results obtained by histological, hematocytological, electronmicroscopic and enzymohistochemical methods were as follows: 1) The manifestation types of leprous lesion were significantly influenced by functional activity of the reticuloendothelial system of the host. 2) Lepra cells developed from the histiocyte and its precursor, the prehistio-cyte, in the loose connective tissue proper. 3) The functional maturity of histiocytes as indicated by the digestion activity on the bacilli determined whether the involved cells were transformed into the lepra cell or not.