ANTI-HUMAN KAPPA-OPIOID RECEPTOR ANTIBODIES - CHARACTERIZATION OF SITE-DIRECTED NEUTRALIZING ANTIBODIES SPECIFIC FOR A PEPTIDE KAPPA-R(33-52) DERIVED FROM THE PREDICTED AMINO-TERMINAL REGION OF THE HUMAN KAPPA-RECEPTOR

Site-directed polyclonal Abs specific for a synthetic peptide with seq uence homology to the predicted N-terminal sequence of the human kappa opioid receptor [anti-kappa R-(33-52)] are capable of binding to norm al human cells and cell lines expressing mRNA specific for the human k appa receptor. Flow cytometric analysis of 1) a neuronal cell line (NT 2), 2) blood-derived CD14(+) monocytes, 3) monocyte-like cell lines (U 937 and THP 1), 4) blood-derived CD3(+) T cells and a T cell line, and 5) human B cell lines bound anti-kappa R-(33-52) in a specific manner . Anti-kappa R-(33-52) was also found to specifically neutralize the i mmunosuppressive activities associated with the kappa R-selective agon ist U50,488H. This antiserum was found to block U50,488H-mediated inhi bition of 1) Staphylococcus aureus Cowen strain I-induced B and T lymp hocyte proliferation, 2) PHA-induced T lymphocyte proliferation, and 3 ) S. aureus Cowen strain I-induced IgG production. However, this antis erum failed to neutralize mu R-selective agonist (Tyr-D-Ala-Gly-NMe-Ph e-Gly-ol)-mediated suppression of IgG synthesis. Finally, the kappa R- selective antagonist nor-binal-torphimine hydrochloride inhibits the b inding of anti-kappa R-(33-52) to the U937 cell line. These results su ggest that anti-kappa R-(33-52) specifically interacts with the human kappa R molecule. Studies conducted with anti-kappa R-(33-52) indicate d that this antiserum effectively blocked U50,488H-mediated immunosupp ression, but by itself did not enhance or suppress lymphocyte activati on. These data suggest that anti-kappa R-(33-52) 1) does not interact with the effector binding site of the receptor, but sterically interfe res with U50,488H binding to the receptor; and/or 2) the antiserum int eracts with a secondary binding site that is important for ligand bind ing, but may not be involved in signal transduction.