Opioid dependency and T-helper cell functions in rhesus monkey.

Administration of morphine sulfate to rhesus monkeys may activate the quiescent lymphocyte for proliferation, induce a transient increase in the T cell proliferative response to mitogens, and cause an enhanced interleukin-2 release from the mitogen-stimulated lymphocytes. However, longitudinal studies of the animals dependent upon morphine or L-a-acetyl-methadol, a long-acting opioid, revealed an overall immunosuppression of T helper functions. In vitro studies using morphine and its antagonist naloxone suggested that the immunosuppression was not a result of a direct interaction between the opioids and conventional opiate receptors which might have been present on the lymphocytes. The studies also showed the importance of measuring [3H]thymidine incorporation rather than its uptake into cells to assess T cell activation.