Extracellular killing of Leishmania promastigotes and amastigotes by macrophage precursors derived from bone marrow cultures.
Flagellates of the genus Leishmania are obligate intracellular parasites of vertebrates including man. The microorganisms reside and multiply inside the phagolysosomes of cells of the mononuclear phagocyte lineage. We here report on the spontaneous leishmanicidal activity exerted extracellularly by immature cells of the mononuclear phagocyte lineage. Highly purified, bone marrow-derived macrophage precursor cells displayed a strong spontaneous leishmanicidal activity already at very low effector/target rations (3:1, 6:1). This leishmanicidal activity was effective against both promastigotes and amastigotes as targets. The cytotoxic effect was evident within 4 h and maximal after 12 h of effector-target organism cocultivation, as determined by a radiolabel-release assay. An intimate cell-cell contact seemed necessary for the parasites to be killed.
Baccarini
M
M
Fraunhofer-Institute for Toxicology and Aerosol Research, Department of Immunology, Hannover, Federal Republic of Germany.
Hockertz
S
S
Kiderlen
A F
AF
Lohmann-Matthes
M L
ML
D000818:Animals; D001854:Bone Marrow Cells; D002454:Cell Differentiation; D002478:Cells, Cultured; D005260:Female; D007891:Leishmania / Q000254:growth & development; D008264:Macrophages / Q000166:cytology / Q000502:physiology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL