DOES PROLONGED ORAL TREATMENT WITH SUSTAINED-RELEASE MORPHINE TABLETSINFLUENCE IMMUNE FUNCTION

Opioids such as morphine are the mainstay of acute and chronic pain tr eatment. The purpose of this study was to investigate the immunosuppre ssive effects of morphine in patients with pain syndromes. We investig ated 10 patients with chronic pain syndromes undergoing treatment with oral sustained-release morphine (30-240 mg/d) before and after 1, 4, and 12 wk of treatment compared with healthy control subjects without morphine treatment. Immunological variables of the cellular and humora l immune axis showed that 1) total lymphocyte counts and the distribut ion of lymphocyte subpopulations, including helper T-cell/suppressor c ytotoxic T-cell ratios (CD4/CD8 ratios), did not change compared with baseline or healthy control subjects; 2) proliferation of peripheral m ononuclear cells (PMC) was not impaired by morphine treatment; 3) inte rleukin 2 production increased after 4 wk of treatment with morphine; and 4) immunoglobulin (Ig) production was reduced before initiation of therapy in pain patients and decreased further during morphine treatm ent, whereas Ig concentrations in the circulation remained at normal l evels. These results indicate that treatment with oral, sustained-rele ase morphine does not have a suppressive effect on overall PMC functio n. On the other hand, Ig production was impaired in patients with chro nic pain and was further suppressed by morphine. Whether this suppress ion of humoral immune function has a clinical impact on the immune sys tem as a whole remains to be determined. Implications: Treatment of pa tients with chronic pain with oral, sustained-release morphine does no t influence cellular immune function, but it suppresses the already at tenuated production of immunoglobulins.