Receptor cross talk between neutrophil FPR1 and PAFR/CXCR1/2 determined as superoxide production.

<p>Human neutrophils desensitized with fMIFL were cross-desensitized to IL8 (<b>A</b>) but primed in their response to PAF (<b>B</b>). Neutrophils (10<sup>5</sup> cells, 37°C) were first activated by the FPR1 specific agonist fMIFL (0.1 nM, added at time indicated by the arrows to the left) leading to receptor desensitization (solid lines in <b>A</b> and <b>B</b>). A second stimulus (<b>A</b>; IL8, 100 ng/ml, <b>B</b>; PAF, 100 nM) was added to the cells (solid lines) at the time point indicated by the arrows to the right. Activation of naïve (non-desensitized) neutrophils by IL8 (<b>A</b>) and PAF (<b>B</b>) was determined in parallel and is shown for comparison (broken lines). A representative experiment is shown, n>5. Abscissa, time of study (min); Ordinate, superoxide production (counts per minute×10<sup>6</sup>; Mcpm).</p>