The mF1Pal₁₆ pepducin activates primarily Fpr2 in mouse neutrophils.

<p><b>A)</b> Mouse neutrophils (5 x 10⁴ cells) were activated by addition of the mF1Pal₁₆ pepducin (1 μM). <b>Inset:</b> Dose-dependent activation of mouse neutrophils by mF1Pal₁₆. Data is normalized to the maximal response and curve fitting was performed by non-linear regression using the sigmoidal dose-response equation (variable slope, HillSlope 0.9). EC₅₀ value and 95% confidence interval (mean ± SD) were from three independent experiments with individual mouse. <b>B)</b> The mF1Pal₁₆ induced cell activation in mouse neutrophils (5 x 10⁴ cells) isolated from WT (black bar) and Fpr2^-/- (grey bar) mice. Cells were incubated for 5 min at 37°C before the addition of mF1Pal₁₆ (1 μM) and the NADPH-oxidase activity was measured over time. The peak values obtained were compared and the results are expressed as percent of the peak activity induced by fMIFL (10 nM) in cells derived from each individual mouse (mean ± SD) from three independent experiments with individual mouse. * <i>p</i> ≤ 0.05. <b>C)</b> Cross-desensitization between PSMα2 (50 nM) and mF1Pal₁₆ (1 μM) in WT mouse neutrophils. Cells first received (indicated by the first arrow) PSMα2 (solid line) or mF1Pal₁₆ (dashed line) and when the response had declined, a second stimulation (indicated by the second arrow) was induced by mF1Pal₁₆ (solid line) or PSMα2 (dashed line). <b>Inset:</b> Cross-desensitization between mF1Pal₁₆ and fMIFL in mouse neutrophils. Cells first received (indicated by the first arrow) fMIFL (10 nM, solid line) or mF1Pal₁₆ (1 μM, dashed line) and when the response had declined, a second stimulation (indicated by the second arrow) was induced by mF1Pal₁₆ (1 μM, solid line) or fMIFL (10 nM, dashed line). The release of superoxide anions was continuously measured. Representative curves out of three independent experiments from individual mouse are shown. <b>D)</b> Effect of Fpr1 inhibitor Boc2 (2 μM, black bar) and Fpr2 antagonist (1 μM, grey bar) on the mF1Pal₁₆ (500 nM) response. The data are from five independent experiments with individual mouse (mean ± SD) and One-way ANOVA with Dunnett’s multiple comparisons test in comparison to the mF1Pal₁₆ control response was used for statistics.