Identification of κ‐ and δ‐opioid receptor transcripts in immune cells

Publisher Website
Google Scholar
Abstract
To investigate the role of opioids as direct modulators of the immune response, we have searched for expression of the recently cloned δ, μ and κ opioid receptors in immune cells. We have devised a reverse transcriptase‐polymerase chain reaction strategy which specifically detects a region spanning putative transmembrane regions 2 to 7 for each transcript in both human and mouse immune cells. In human peripheral blood lymphocyte and monocyte preparations, δ was undetectable while the κ transcript was present. The analysis of human cell lines revealed low but significant levels of δ opioid receptor transcripts in T, B or monocyte cell lines while the κ transcript was found in B cell lines only. Investigation of murine cells showed the presence of transcript for the δ receptor in splenocytes and in some T and B cell lines. Unexpectedly, no expression of the μ receptor was detected. Sequence analysis of PCR products demonstrated nucleotide identity between immune and neuronal transcripts, indicating that they derive from the same genes. In conclusion, our results lead to the identification of κ and δ opioid receptor transcripts in immune cells.