δ opioid receptor expression is induced by concanavalin A in CD4+ T cells

Expression of delta opioid receptor mRNA in CD4+ T cells purified from Con A-stimulated murine splenocytes was demonstrated by reverse transcription-PCR and sequencing of the PCR products. mu and kappa opioid receptor mRNAs were not detected. Similar results were obtained in a single isolation of CD8+ T cells from Con A-stimulated splenocytes. mRNA for the delta opioid receptor was not detected in CD4+ T cells purified from either freshly isolated splenocytes or splenocytes cultured without Con A, and incubation of purified CD4+ T cells with Con A did not induce delta opioid receptor mRNA. It appears that quiescent CD4+ T cells do not express classic opioid receptors, but the delta-type receptor can be induced upon activation.