CYCLOHEXIMIDE TREATMENT OF MOUSE MAST-CELLS INHIBITS SEROTONIN RELEASE - EVIDENCE OF A REQUIREMENT FOR NEWLY SYNTHESIZED PROTEIN IN THE EXOCYTOTIC RESPONSE

Treatment of mouse peritoneal mast cells and mouse bone marrow-derived cloned mast cells with the protein synthesis inhibitor cycloheximide led to a marked abrogation of serotonin (5-hydroxytryptamine; 5-HT) release induced by a range of activators including antigen, anti-immunoglobulin E (anti-IgE) antibody, calcium ionophore A23187, and the polycation polylysine. Significant inhibition (28%) of IgE-mediated secretion was attained after incubation of peritoneal cells for only 2 hr, and inhibition progressed over a 24 hr period, reaching >80% after 15 hr. When peritoneal mast cells were exposed to cycloheximide and then washed and returned to culture conditions, a substantial recovery of responsiveness to anti-IgE was seen after 5 hr. Under the same conditions to those used in functional studies, cycloheximide inhibited protein synthesis, measured as incorporation of [S-35]-methionine, by purified peritoneal mast cells and cloned mast cells to 18.5% and 7.9% of control levels, respectively. These results show that synthesis of new protein over a period of a few hours is required to render mast cells fully responsive to stimuli that act via the IgE receptor, and to certain other stimuli that are receptor-independent.