Continuous granule exocytosis and granzyme B secretion upon simultaneous stimulation of basophils with C5a and IL-3. Shown is a time course of basophil exocytosis, GzmB formation and release, lipid mediator formation, and cytokine expression in response to IL-3 and C5a. Basophils were cultured in medium alone, with IL-3 (10 ng/mL), with C5a (10 nM), or with the combination of C5a and IL-3 for indicated time periods. C5a was added to the cells at 4°C before culture at 37°C. IL-3 addition followed 30 minutes later at 37°C. (A) GzmB and the basophil granule marker histamine were measured in cell supernatants and pellets. (B) LTC4 formation and cytokine secretion (IL-4 and IL-13) were measured in the cell supernatants only. Mean values of triplicates of a representative experiment (out of 3) are shown.
