metenkephalin induced escape from dexamethasone immunosuppression the present study was undertaken to examine whether and what type of interaction occurs between a synthetic glucocorticoid dexamethasone dex and an opioid peptide metenkephalin menk upon superoxide anion o2 release from human polymorphonuclear cells pmn menk 108 m abolished suppressed o2 release from pmns treated with 107 m dex this was the case in unstimulated but not in pmns stimulated with pma the effect of menk was mediated through pertussistoxin ptx sensitive gprotein and since it was abolished by h7 probably involves protein kinase c pkc as a second messenger system thus menk can abolish dex induced suppression of o2 release from human pmns possibly through the interaction of second messenger pathways