Production of monoclonal antibodies against human growth hormone releasing hormone and their use in an enzyme-linked immunosorbent assay (ELISA)

Two murine monoclonal antibodies (mAbs) specific for human growth hormone releasing hormone (GHRH-44-NH 2) were produced from a fusion of spleen cells from a BALB/c mouse immunized with GHRH-conjugated BSA with SP 2/0 myeloma cells. The antibodies were of the IgG1κ, and IgG2b-κ isotypes. The binding of both antibodies to GHRH-coated plates was inhibited by a 30–44 amino acid fragment but not by a 1–26 fragment. Thus, both antibodies are directed against the carboxy terminus of the peptide. Furthermore, both antibodies bind to the same epitope on the 30–44 amino acid portion since they cross-inhibit each other's binding to intact GHRH. Using these mAbs, a direct binding GHRH enzyme-linked immunosorbent assay (ELISA) was developed which had at least detectable dose of 0.3 pg. The availability of these antibodies and their use in ELISA methodology permits consistent and specific detection of GHRH in a non-isotope assay. They should prove of value in screening acromegalic patients for ectopic sources of GHRH secretion and in studies of ontogenic analysis of GHRH production.