ANTIIDIOTYPIC ANTIBODIES - A USEFUL ALTERNATIVE FOR STUDYING THE BIOCHEMICAL EXPRESSION OF MU DELTA OPIOID BINDING-SITES IN MAMMALIAN BRAIN/

A polyclonal antiserum was produced against opioid binding sites using an anti-idiotypic approach whereby antibodies directed against the op ioid agonist DSLET were used as immunogen. The anti-idiotypic antiseru m recognized specific brain proteins with molecular masses of 76 +/- 4 , 73 +/- 4 and 59 +/- 3 kDa, respectively. The immunolabeling of these proteins was mainly inhibited by mu, delta opioid agonists and a gene ral antagonist, naloxone. The inhibition of immunoprecipitation by opi oid agonists and antagonist and the developmental expression of these immunoreactive proteins found to occur during brain ontogeny strongly suggest that these three proteins were mu, delta but not kappa opioid binding sites. The anti-idiotypic antiserum both inhibits H-3-DADLE bi nding and mimics the inhibitory agonist effects on the stimulated cAMP level of NG 108-15 cells which expressed delta opiate receptors. Nume rous mammalian brain opioid binding sites were labeled, due to the fac t that the binding site was the epitope recognized by the anti-idiotyp ic antibodies. From the numerous studies performed with a view to char acterizing the specificity of the anti-idiotypic antibodies, it was st rongly suggested that the anti-idiotypic antibodies specifically recog nize mu/delta opioid binding sites and they can therefore be powerful tools for studying the biochemical expression of these opioid binding sites in mammalian brains.