Fig. 1.
Effect of phagocytic stimulation on the expression of CXCR1 and CXCR2 in human neutrophils.
(A,B) PMNs were incubated alone for 15 minutes at 37°C (1) or treated with nonopsonized (2) or opsonized S cerevisiae(OSC) (3) at an OSC/PMN ratio of 2:1. (C) Dose dependence of the effect of phagocytic stimulation with OSC on the expression of CXCR1 (closed bars) and CXCR2 (open bars, mean of triplicates ± SD). (D) Time dependence of the expression of CXCR1 (▴) and CXCR2 (●) in phagocytosing neutrophils (closed symbols) and in control cells (open symbols; mean ± SD, n = 3). (E,F) Effect of phenantroline at 2 mM (line 3) on the modulation of CXCR1 (E) and CXCR2 (F) expression after OSC (2), compared with untreated PMNs (1). The expression levels in panels A, B, E, F, and H are displayed as mean fluorescence intensity (MFI) of duplicate samples; the difference between double FACScan estimates was in the range of 2% to 10%. Each PMN sample was stained with irrelevant monoclonal antibody of IgG1 isotype, and the resulting MFI was subtracted from MFI with specific mAb. To test a possible effect of the OSCs themselves on the PMN-staining procedure, OSC suspension was added to control PMNs at the end of incubation, along with sodium azide, following by a full staining procedure: no effect of OSC was detected (not shown). Results similar to those of panels A and B were obtained in 16 separate experiments; dose dependence similar to that of panel C was obtained in 3 experiments; time dependence similar to that of panel D, in 5 experiments; and the effect of phenantroline was reproduced in 4 separate experiments. (G) CXCR1 (closed bars) and CXCR2 (open bars) mRNA expression in human neutrophils after treatment of PMNs with OSC. Results are expressed as a ratio of CXCR mRNA to β2-microglobulin mRNA as external control. (H) Confocal images showing the distribution of CXCR1 and CXCR2 in PMNs incubated alone (Hi,ii; upper section), treated with IL-8 at 500 ng/mL for 15 minutes (i,ii; lower section) or in PMNs treated with OSC (iii-v); corresponding MFI data are shown below the pictures (Hiii-v) Fluorescence is shown in the lower part of the pictures, and transmission light microscopy of the same cells is shown in the upper part (pN indicates PMN phagocytosing OSC; N, nonphagocytosing PMN; OSC, nonspecific fluorescence of OSC at 543 nm).