GM-CSF, LPS and Siglec-F signaling enhance IL-33-induced secretion of IL-4 and IL-13 from eosinophils. (A) BMDE were cultured with <t>IL-5</t> and indicated concentrations of IL-33 and LPS. (B) BMDE were cultured in 10 ng/ml IL-5 and IL-33 in the presence or absence of 10 ng/ml GM-CSF. In addition, anti-Siglec-F, isotype control antibody or no antibodies were added to the culture. (C) BMDE were cultured in 10 ng/ml IL-5 and IL-33. In addition, the p38 kinase was blocked with 5 μM SB203580 and DMSO was used as solvent control. All supernatants were analyzed at 24 hours after onset of culture by IL-4 and IL-13 specific ELISAs. Bars show the mean + SD from one of two independent experiments with similar results (A; n = 4) the mean + SD from one of three independent experiments (B; n = 4) and mean + SEM pooled from two independent experiments (C; n = 8) *p