Effects of neutrophils on histamine release from mast cells

To determine whether neutrophils (NP) contribute to immediate anaphylaxis, the effects of NP on histamine release from mast cells (MC) were studied and changes in the NP morphology were investigated. When rat peritoneal MC and pleural NP collected from actively sensitized rats were mixed and challenged with antigen (trichosanthin), histamine release from MC was significantly increased. This promotive effect of NP on antigen-induced histamine release from MC was dosage-dependent. The observation of scanning and transmission electron microscopy showed that NP were activated and secretion was resulted. It is suggested that NP may be activated in immediate anaphylaxis and secrete some mediators which could promote histamine release from MC. Quercetin may inhibit the promotive effect of the NP on histamine release and the secretion of the NP while ketotifen and isoproterenol have no influence on this promotive effect.