FIGURE 11.

Live Leishmania parasites are required for their efficient engulfment by naive human neutrophils. A, fluorescent promastigotes of L. panamensis transfected with the p6.5-egfp construct were untreated (LpGFP) or treated with 1% paraformaldehyde for 10 min (LpGFP-PFM), and then the fluorescence signal from the parasites was measured by flow cytometry as mean fluorescence intensity (MFI). B, human polymorphonuclear neutrophils (PMN) were incubated for 3 h with LpGFP or LpGFP-PFM, and the percentage of infection was assessed by flow cytometry. C, human neutrophils were incubated with LpGFP or LpGFP-PFM in the absence or presence of 1 mg/ml of opsonized zymosan (OZ), and then the percentage of infection was assessed by flow cytometry as above. Data shown are means of 3 independent experiments ± S.E. Asterisks denote significant differences with viable parasites in B, and with naive neutrophils in C (**, p < 0.01) by Student's t test.