Enkephalins and the immune system (Abstract)
This study reports the in vitro influence of morphine, dextromoramide, levo-moramide and methionine-enkephalin upon normal human T blood lymphocytes by using the active and total rosette tests, Morphine and dextromoramide inhibited the percentage of active T rosettes. This effect was completely reversed in the presence of naloxone, their specific antagonist. The specificity was further demonstrated by the absence of the effect of levo-moramide, the inactive enantiomere, upon the rosette system. Methionine-enkephalin increased the percentage of active T rosettes. This effect was specifically inhibited by naloxone. These observations suggest that normal human blood T lymphocytes bear surface receptor-like structures for morphine, dextromoramide and methionine-enkephalin. Since non-opiate receptors have also been described on B lymphocytes, the ‘two hits opioid lymphocyte receptor hypothesis’ is presented. This theory postulates that opioid peptides can modulate the co-operation between T and B lymphocytes. Finally, such findings may provide a link betweeen the central nervous system and the immune system, and enkephalins may be the humoral mediators between the two systems.