1. Characterization of [3H]morphine binding to interleukin-1-activated thymocytes.
- Author
-
Roy S, Ge BL, Loh HH, and Lee NM
- Subjects
- Animals, Binding Sites, Bone Marrow metabolism, Brain metabolism, Cell Membrane metabolism, Dithiothreitol, Endopeptidases, Lymphocyte Activation drug effects, Male, Mice, Mice, Inbred ICR, Phospholipases, Receptors, Opioid metabolism, Thermodynamics, Thymus Gland cytology, Thymus Gland drug effects, Time Factors, Tritium, Interleukin-1 pharmacology, Morphine metabolism, Thymus Gland metabolism
- Abstract
We have previously reported that interleukin-1-induced proliferation of thymocytes is accompanied by the appearance of [3H]morphine binding sites on these cells. In the present study, we have characterized these binding sites. They differ from classical opioid receptors in the brain in several ways, including: 1) lack of stereoselectivity; 2) relatively low affinity (Kd = 50 nM) and high capacity (Bmax = 3 pmol/mg of protein); 3) binding is strongly inhibited by Ca++, Mg++, Mn++ and Cl- ions and 4) binding is inhibited by proteinase K or E and by phospholipase A2 but not trypsin treatment of thymocyte membranes. The binding sites, which were found largely on the CD4+ subset of T-cells, also showed a preference for opioid alkaloids over peptides. These [3H]morphine binding sites may mediate a negative feedback effect on interleukin-1-induced proliferation of thymocytes in vivo.
- Published
- 1992