Phytohemagglutinin-dependent T-cell proliferation is not impaired by morphine.

Opioids have been reported in the literature to have immunosuppressive properties. Thus, we investigated the influence of morphine, morphine-3-glucuronide and morphine-6-glucuronide in vitro on phytohemagglutinin-stimulated proliferation of peripheral mononuclear cells from healthy humans. Furthermore, the effects of a 1-week treatment with morphine in a range of 30-240 mg/day on proliferation of lymphocytes from patients with chronic pain syndromes were evaluated. In addition, human peripheral mononuclear cell membranes were tested for specific opioid radioligand binding. The results show that i) morphine and its main metabolites do not influence mitogen-induced T-cell proliferation, ii) treatment of patients with sustained release morphine for 1 week did not impair the lymphocyte proliferative response, and iii) no specific binding of mu-, delta- and kappa-radioligands could be demonstrated to membranes of peripheral lymphocytes obtained from healthy humans. These results do not indicate an impairment of phytohemagglutinin-induced T-cell proliferation during pain treatment with sustained release morphine.