Cell shape of polymorphonuclear leukocytes is influenced by opioids.

The effects of beta-endorphin(beta-End), an endogenous opioid, were tested in vitro on shape changes in polymorphonuclear leukocytes (PMNs). Cell shape changes indicate alterations of the functional status of the cells. Within 2 min, beta-End but not the opioid alkaloid levorphanol or the antagonist, diprenorphine, induced a cell spreading. Subsequently, beta-End and levorphanol (10(-8) M), but not the dextrorotatory isomer, stimulated an elongation of the cells. Both effects of beta-End could be antagonized by diprenorphine in an equimolar concentration. Thus, the effects were stereo-specific and antagonizable. In this test system, the morphological changes evoked by beta-End were equal to the effects of FMLP, a chemotactic substance, used as a reference. Our findings indicate that endogenous opioids might play a role in modulating the initial phase of the PMNs' offensive behaviour, presumably cell adherence and motility.