Dasatinib partially inhibits neutrophil functions triggered by G-protein–coupled receptors. Human neutrophils pretreated with the indicated concentrations of dasatinib with or without 10μM cytochalasin B (CB) were stimulated with 1μM fMLP (A-E), 100 ng/mL of human IL-8 (F-H), 50 ng/mL of C5a (I), or 50 ng/mL of LTB4 (J), followed by measurement of the respiratory burst (A), lactoferrin release (B), flow cytometric analysis of the expression (C,F) and activation (D,G) of CD11b, or assessment of phosphorylation of the ERK or p38 MAPKs by immunoblot and analysis of gelatinase release by in-gel zymography (E,H-J). The kinetic/bar graphs in panels A and B show mean and SD of representative experiments, and the dose-response curves in these panels and bar graphs in panels C and D and F and G show means and SEM of the percent response. Mean fluorescence intensity values of isotype control–stained samples were subtracted in panels C and D and F and G, and the resulting fluorescence was expressed as a percentage of that in the indicated samples. Each set of data were obtained from 3-5 independent experiments. Panels E and H through J are representative of 3 independent experiments. The mean and SEM of phosphorylation of the various MAPKs in the stimulated samples after subtraction of unstimulated controls in the presence of 10nM, 100nM, and 1μM dasatinib was, respectively: 103% ± 10%, 99% ± 14%, and 77% ± 17% (E; p38 MAPK); 99% ± 9%, 94% ± 6%, and 100% ± 2% (E; ERK); 90% ± 17%, 53% ± 5%, and 16% ± 5% (H; p38 MAPK); 123% ± 39%, 112% ± 11%, and 169% ± 42% (H; ERK); 102% ± 52%, 75% ± 27%, and 24% ± 12% (I; p38 MAPK); 98% ± 5%, 98% ± 12%, and 195% ± 55% (I; ERK); 113% ± 53%, 79% ± 29%, and 62% ± 60% (J; p38 MAPK); and 89% ± 14%, 173% ± 32%, and 236% ± 49% (J; ERK) of that in the absence of dasatinib.
