IDENTIFICATION OF KAPPA-OPIOID AND DELTA-OPIOID RECEPTOR TRANSCRIPTS IN IMMUNE CELLS

To investigate the role of opioids as direct modulators of the immune response, we have searched for expression of the recently cloned delta , mu and kappa opioid receptors in immune cells. We have devised a rev erse transcriptase-polymerase chain reaction strategy which specifical ly detects a region spanning putative transmembrane regions 2 to 7 for each transcript in both human and mouse immune cells. In human periph eral blood lymphocyte and monocyte preparations, delta was undetectabl e while the kappa transcript was present. The analysis of human cell l ines revealed low but significant levels of delta opioid receptor tran scripts in T, B or monocyte cell lines while the kappa transcript was found in B cell lines only. Investigation of murine cells showed the p resence of transcript for the delta receptor in splenocytes and in som e T and B cell lines. Unexpectedly, no expression of the mu receptor w as detected. Sequence analysis of PCR products demonstrated nucleotide identity between immune and neuronal transcripts, indicating that the y derive from the same genes. In conclusion, our results lead to the i dentification of kappa and delta opioid receptor transcripts in immune cells.