Immunomodulatory effect of naloxone in duodenal ulcer patients

The effect of a single dose of the opiate receptor antagonist naloxone (NAL) on some immune parameters in chronic duodenal ulcer patients and healthy controls was investigated. Twelve hospitalized men, aged 19-23 years (nine duodenal ulcer patients and three controls) were given NAL intravenously at a dose of 0.03 mg/kg. Blood samples were drawn before and 30 and 150 min after NAL injection. Results obtained in duodenal ulcer patients and healthy subjects revealed the same direction of changes despite a rather wide scatter. Baseline NK cell activity was lower in duodenal ulcer patients than in healthy persons. In approximately one fourth of patients the changes in individual parameters observed following NAL injection were slight. Numbers of total lymphocytes, Th, Ts, NK cells, monocytes and Th/Ts ratio did not significantly change after NAL administration. T-lymphocyte counts moderately decreased at 30 min after NAL injection. NAL did not affect spontaneous IL-2 receptor expression and it moderately increased PHA-induced IL-2 receptor expression in most of the investigated persons. IL-2 generation and NK cell activity slightly, but significantly, increased at 30 min following NAL injection. NAL markedly inhibited lymphocyte proliferation in an AMLR test 30 min after its administration. Most of the investigated parameters returned to their initial levels after 150 min following NAL administration. The studies showed that not only endorphins and enkephalins may have an immunomodulatory action, but NAL, their antagonist, may also affect some functions of the immune system in humans, although its action is transient.