title: Multiplication of Leishmania in human macrophages in vitro.
abstract: To facilitate in vitro studies of the immunology of human leishmaniasis, we developed a method of growing pathogenic Leishmania in human monocyte-derived macrophages. After 6 days of incubation, adherent mononuclear cells were infected with Leishmania donovani amastigotes obtained from infected hamster spleen cells or with L. tropica amastigotes obtained from infected BALB/c tissue mouse footpad. Forty-eight percent of the macrophages were initially infected, with a mean of 3.0 amastigotes per infected macrophage. After 6 days of incubation, 59% of macrophages were infected and contained 8.8 amastigotes per infected macrophage, representing 2.9-fold multiplication. Electron microscopy revealed the presence of dividing parasites within phagolysosomes. These observations indicate that Leishmania survive and multiply within human monocyte-derived macrophages despite fusion of secondary lysosomes with the parasitophorous vacuole.
mesh_terms: D002448:Cell Adhesion; D006801:Humans; D007891:Leishmania / Q000254:growth & development*; D008264:Macrophages / Q000166:cytology / Q000469:parasitology*