Binding site analysis of opioid receptors using monoclonal anti-idiotypic antibodies

William Gerard Conroy, Purdue University

Abstract

Structural relatedness between the variable region of anti-ligand antibodies and opioid binding sites allowed the generation of anti-idiotypic antibodies which recognized opioid receptors. Two IgG$\sb3$k antibodies which bound to opioid receptors were obtained when an anti-morphine antiserum was the idiotype. Both antibodies bound to opioid receptors, but only one of these blocked the binding of ($\sp3$H) naloxone. The antibody which did not inhibit the binding of ($\sp3$H) naloxone was itself displaced from the receptor by opioid ligands. The unique binding properties displayed by this antibody indicated that anti-idiotypic antibodies are not always a perfect image of the original ligand, and therefore may be more useful than typical ligands as probes for the receptor. When an idiotype which resembled the antagonist-state of the opioid receptor was used to produce anti-idiotypic antibodies, none of the anti-idiotypic antibodies that were obtained recognized the binding site on the opioid receptor. Thus, a separate binding site specific for antagonists may not exist on the opioid receptor. An auto-anti-idiotypic technique was successfully used to obtain anti-opioid receptor antibodies. Another IgG$\sb3$k antibody that blocked the binding of ($\sp3$H) naloxone to rat brain opioid receptors was obtained when a mouse was immunized with naloxone conjugated to bovine serum albumin. These data confirmed that an idiotype-anti-idiotype network which can generate an anti-receptor antibody normally functions when an opioid ligand is introduced into an animal in an immunogenic form.

Degree

Ph.D.

Advisors

Isom, Purdue University.

Subject Area

Pharmacology

COinS