DIFFERENTIAL EXPRESSION OF OPIOID RECEPTOR GENES IN HUMAN LYMPHOID-CELL LINES AND PERIPHERAL-BLOOD LYMPHOCYTES

The existence of receptors for opioid compounds on cells of the immune system has long been hypothesized, but has been very difficult to dem onstrate unequivocally. We have used reverse-transcription polymerase chain reaction to obtain cDNA clones from the human MOLT-4 and CEM-3 T -leukemic cell lines Which are nearly identical to portions of the del ta and kappa opioid receptor cDNAs recently isolated from human brain and placenta, respectively. Northern analyses with riboprobes derived from the delta and kappa opioid receptor clones indicate these sequenc es are expressed at low levels in human peripheral blood lymphocytes a nd in several human lymphoid cell lines. Sequences corresponding to th e mu opioid receptor cDNA were not detected in this study. These resul ts suggest that delta and kappa opioid receptors may be responsible fo r mediating some direct effects of opioids in immune cells.