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 b lot analyses revealed the expression of OR protein in DC. Radioreceptor ass ay 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 ind uce T cell proliferation in an MLR assay. Importantly, expression of functi onal OR on DC was significantly increased upon TNF-alpha -induced DC matura tion. Thus, these data suggest a new mechanism of opioid-dependent neuroend ocrine immunomodulation. (C) 2001 Elsevier Science B.V. All rights reserved .