The Prominent Role of Neutrophils during the Initial Phase of Infection by Leishmania Parasites
Exposure of neutrophils to L. major decreases spontaneous but not macrophage-induced apoptosis. L. major-recruited C57BL/6 neutrophils (PMNs) and macrophages (M) were isolated from the peritoneal cavity 4 hours or 24 hours after L. major injection i.p., respectively. (a) MACS-purified PMNs were cultured for 24 hours in presence or in absence of metacyclic L. major (L. major:PMN ratio 1 : 5). Cells were collected, labeled with Annexin-V, 7AAD, and the 1A8 mAb (Ly6G) and PMN apoptosis analyzed by FACS, gating on the 1A8+ PMN population. Early apoptotic cells are Annexin-V+ 7AAD-, and late apoptotic/necrotic cells are Annexin-V+7AAD+. (b) PMNs were cultured in presence of fixed M(PMN : M1 : 2) with or without parasites, and 24 hours later, neutrophils were analyzed as in A. Data are representative of three independent experiments.