Receptor cross talk between neutrophil FPR1 and PAFR/CXCR1/2 determined as superoxide production.
Human neutrophils desensitized with fMIFL were cross-desensitized to IL8 (A) but primed in their response to PAF (B). Neutrophils (105 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 A and B). A second stimulus (A; IL8, 100 ng/ml, 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 (A) and PAF (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×106; Mcpm).
