AbstractThe effects of acute and chronic zidovudine (AZT) administration on immunologic test responses of mice were studied. The effects of AZT administration combined with morphine or methadone treatment, were also studied separately comparing the effects of each drug.We noted that AZT-treatment did not modify the T-lymphocyte subsets (L3T4/LyT2rate), whereas morphine-treatment and AZT plus morphine treatment decreased the percentage of T helper cells.Acute and chronic AZT-treatment increased Natural Killer cell (NK) activity and also recovered the decreased NK cell activity produced by morphine-treatment.AZT-treatment, morphine-treatment, AZT plus morphine treatment and AZT plus methadone treatment strongly depressed the phagocytic physiological activity of Polymorphonuclear leukocytes (PMNs).Another evidence of immunologic responsiveness against AZT was the reduction of the mitogenic and antigenic response of lymphocytes.These results suggest a negative role of AZT-treatment especially on phagocytic activity and confirms a depressive effect of morphine-treatment on several immune functions studied. Furthermore, there is no indication of additive or synergistic toxic effects of AZT, morphine and methadone on the immune functions above that seen with each of these drugs when tested alone.