Effects of in vivo and in vitro administration of morphine sulfate upon rhesus macaque polymorphonuclear cell phagocytosis and chemotaxis

The effects of morphine administration were evaluated upon the polymorphonuclear (PMN) cell activities of rhesus macaques. Sixteen animals were used in the study. Seven macaques were treated with saline and nine animals were administered morphine in the form of morphine sulfate, following a control period of saline injections. The dosage regime was initiated at 1 mg of morphine sulfate per kg of b.wt., 3 times daily, with incremental steps to a stable dose of 5 mg/kg, 3 times daily. PMN cells prepared from morphine- treated animals showed a marked, transient reduction in their ability to kill ingested yeast blastospores, although the ingestive capacity of the PMN cells was not impaired. PMN cells prepared from three of the nine morphine-treated animals showed a transient reduction in chemotaxis toward a complement- derived chemotactic factor. In vitro studies on PMN cells prepared from morphine-naive animals suggested that the killing activity and the chemotaxis of the cells were reduced by treatment with 50 pM morphine sulfate, but not with 50 fmol of morphine sulfate.