EXPERIMENTAL CUTANEOUS LEISHMANIASIS - TRANSMISSION ELECTRON-MICROSCOPY OF THE INOCULATION SITE

Tissue response against inoculation of Leishmania (Leishmania) amazone nsis promastigotes in the hind footpad was quite different between two strains of mice: in BALB/c animals there was parasitism of perineuria l cells by the 8th week post inoculation (WPI) and heavy parasitism of macrophages, as well as degenerated extracellular parasites close to collagen fibers at the 39th WPI, whereas in C57BI/6j mice there was he avy parasitism of macrophages at 6th WPI, dermal vessels with high end othelial cell at 21st WPI and well preserved intracellular amastigote forms by 51st WPI. In both animals there was no parasitism of keratino cytes or Langerhans cells. Thus BALB/c mice were useful as an experime ntal model for diffuse cutaneous leishmaniasis and showing a new featu re, parasitism of perineurial cells, whereas C57BI/6j animals show hyp ersensitivity signs, together with a few preserved parasites, only lat e in the course of infection. From a morphological point of view, ther e were no differences in macrophages, or in the interaction between th is target cell and the parasite, between the animal models studied. Th is suggests that the difference in the response of the hosts towards t he parasite could depend on the way in which they activate acellular, i.e. lymphocyte mediated immune, response.