Murine cutaneous leishmaniasis: comparative study on the capacity of macrophages from "healer" and "non-healer" mouse strains to control L. tropica replication.

A comparison has been made between the capacity of macrophages of BALB/c "non-healer" mice and C57BL/6 "healer" mice to deal in vitro with Leishmania tropica (L. tropica) parasites in order to obtain a more detailed picture of the inherent contribution of macrophages to the susceptibility of BALB/c mice to infection with L. tropica and the resulting fatal course of the disease. In comparison to macrophages of C57BL/6 origin, BALB/c macrophages showed a higher parasite uptake and a higher infection rate; they allowed a more rapid transformation of L. tropica promastigotes into amastigotes and displayed less leishmanicidal activities. Lymphokine-rich culture supernatants induced activation of macrophages resulting in killing of L. tropica by macrophages of both, "non-healer" and "healer" mice. These supernatants also induced expression of Ia-antigens on infected "non-healer" and "healer" macrophages. The results of this study clearly point to the critical role of macrophage functions to either support a systemic leishmaniasis or to alternatively mount a protective immune response leading to a self-healing course of the disease.