Identification of delta- and mu-type opioid receptors on human and murine dendritic cells

The purpose of this study was to evaluate mu- and delta -opioid receptors (OR) on human and murine dendritic cells (DC). Expression of Land delta -OR mRNA on DC was demonstrated by RT-PCR. The immunocytochemical and Western blot analyses revealed the expression of OR protein in DC. Radioreceptor assay demonstrated the specific saturated temperature-dependent binding of [H-3]-labeled opioid ligand on DC and B-max = 2.8 +/- 0.3 fmol/10(6) cells and K-D = 4.8 +/- 1.0 nM were calculated by a Scatchard analysis. Finally, OR ligands DADLE and DAGO dose-dependently modulated the capacity of DC to induce T cell proliferation in an MLR assay. Importantly, expression of functional OR on DC was significantly increased upon TNF-alpha -induced DC maturation. Thus, these data suggest a new mechanism of opioid-dependent neuroendocrine immunomodulation. (C) 2001 Elsevier Science B.V. All rights reserved.