A stereoselective blockade by naloxone of opioid and non-opioid-induced granulocyte activation.

Naloxone was found to prevent both opioid and non-opioid-induced migration of human granulocytes in a stereoselective way. Indeed, besides being able to inhibit morphine-induced migration, (-) but not (+), naloxone isomer proved to abolish either casein, serum of fMLP-induced chemotaxis. It is concluded that opioid-induced modulation of granulocyte migration is likely to be mediated through specific receptors, possibly of the mu type. Moreover, the antichemotactic effect of naloxone suggests an involvement of opioid receptors and/or endogenously released opioids in the mechanism of granulocyte activation by different chemoattractants.