Figure 4
Involvement of various neuropeptides (NPs) used at 10−8 M in the modulation of heat-inactivated serum opsonized and nonopsonized M. catarrhalis ATCC 25238 (Mc) and H. influenzae ATCC 49247 (NTHi) engulfment by isolated human polymorphonuclear phagocytes (PMNs) analyzed by flow cytometry. PMNs were incubated with FITC-labeled bacteria for 30 min at 37°C with agitation and analyses of 15,000 PMNs are presented. Shown is fluorescence signal indicated as geometric mean of the FL-1 signal from the gated sample with phagocytosing PMNs. (A) Representative FACs dot plot with gated PMNs and representative histograms of phagocytic uptake of serum-opsonized (black lines) and nonopsonized (grey lines) bacteria by PMNs in the absence of NPs are shown. (B) Histograms represent increased or decreased endocytic uptake of FITC-labeled opsonized versus nonopsonized targets in the presence of indicated neuropeptides (10−8 M). The levels of bacteria ingested, indicated by mean fluorescence intensity (MFI) values are shown. Color lines show test samples in the presence of indicated neuropeptides, grey lines represent bacterial uptake in the absence of neuropeptides. Results are from one experiment representative of three experiments done with separate blood donors. (C) Data are expressed as the percentage of phagocytosis reported with respect to control values (100% = phagocytosis without NPs). Values are means ± SEM of at least n = 5 (M. catarrhalis) and n = 3 (H. influenzae) independent experiments. Differences between control (without NPs) and treatment condition uptake are assigned by asterisks and considered significant if *p < 0.005 and **p < 0.0005 (one-way ANOVA followed by Tuckey’s post hock test).