SCHISTOSOMA-MANSONI - THE PRESENCE AND POTENTIAL USE OF OPIATE-LIKE SUBSTANCES

The present study demonstrates that morphine- and codeine-like molecul es are present in Schistosoma mansoni following HPLC separation and id entification with. an appropriate commercially available antibody. Fur thermore, the endogenous material, corresponding to morphine, mimics a uthentic morphine in Its ability to induce immunocyte rounding and imm obility, an action that is naloxone sensitive. The codeine-like materi al is not found at high concentrations compared to the morphine-like m aterial, indicating, as in mammals and Mytilus edulis, the potential r apid conversion of codeine to morphine. Coincubation with human leukoc ytes increases the endogenous level of this material in adult worms, i ndicating the presence of a positive feedback loop. Last, EDTA, a chel ator of divalent cations, has a strong stimulating effect in the synth esis of morphine-like material by the worm as noted by higher levels o f this material in its presence. Taken together, the results suggest t hat this parasite may utilize this immune downregulating molecule in i ts effort to escape host immunosurveillance as well as in inhibiting a n immune response directed against itself. (C) 1995 Academic Press, In c.