Electron microscopical studies on cutaneous leishmaniasis in Ethiopia. II. Parasite and host cell differences between the localized and the diffuse form.

The ultrastructure of Leishmania aethiopica parasites and their host cells was investigated in lesions of 7 patients suffering from diffuse cutaneous leishmaniasis (DCL) and in lesions of 4 patients with localized cutaneous leishmaniasis (LCL). The appearance of host cells and parasites varied considerably in both disease forms. Host cell variations occurred especially in the number of cytoplasmic vesicles, the size of the parasitophorous vacuoles, and the number of amastigotes per parasitophorous vacuole. Differences concerned the occurrence of a special macrophage-type in DCL-lesions which was characterized by an electron-translucent cytoplasm and a low degree of parasitization, larger parasitophorous vacuoles with higher numbers of amastigotes per vacuole in infected macrophages from DCL-patients, and the number of electron dense granules in host cell vacuoles of DCL-patients. The parasites inducing DCL and LCL significantly differed in size and membrane structure: Amastigotes had a length of 2.27 +/- 0.48 micron and a width of 1.77 +/- 0.40 micron in DCL-lesions, and 1.92 +/- 0.40 micron and 1.48 +/- 0.32 micron in LCL-lesions. Promastigotes obtained from DCL-patients revealed 2078 +/- 308 integral membrane particles (IMP)/micron2 and 892 +/- 246 IMP/micron2 on the P- and E-fracture faces of plasma membranes, while the corresponding values of LCL-derived promastigotes amounted to 1690 +/- 376 IMP/micron2 and 652 +/- 274 IMP/micron2, respectively.