Growth of Leishmania amastigotes in macrophages from normal and immune mice.

An in vitro system of prolonged culture of Leishmania tropica amastigotes in mouse macrophages is presented. The division rate of parasites was monitored by microscopic observations and by 3H-thymidine incorporation. The dynamics of macrophage infection and parasite division are influenced by the initial rate of promastigotes per cells in culture. Parasites multiply, gradually infect and finally destroy all available macrophages from normal mice releasing large numbers of viable amastigotes. Macrophages from immune donors were inferior in their ability to support parasite multiplication and did not survive long periods in culture.