A dual-monoclonal, sandwich immunoassay specific for glucagon like peptide-19–36/7 (GLP-19–36/7)

• A monoclonal antibody specific for the N-terminal neoepitope of GLP-19–36/7 has been generated.
• A first-in-class, dual monoclonal, sandwich immunoassay specific for GLP-19–36/7 was developed.
• The assay is sensitive enough to measure GLP-19–36/7 in fasted individuals.
• The assay could be used to expand our current knowledge of GLP-1 biology.

ObjectiveGlucagon-like peptide-1 (GLP-1) is a peptide hormone secreted by intestinal L-cells which stimulates glucose-dependent insulin secretion. GLP-1 is initially secreted as the active peptide GLP-17–36/7, but rapidly undergoes cleavage by dipeptidyl peptidase 4 (DPP4) to yield the inactive form, GLP-19–36/7. Despite a reduced affinity for the GLP-1 receptor, GLP-19–36/7 may have cardioprotective properties. There is currently no described immunoassay capable of specifically measuring GLP-19–36/7.Design and methodsWe generated a monoclonal antibody specific for the N-terminal neoepitope of GLP-19–36/7. After affinity maturation, we paired this capture antibody with an anti-total GLP-1 monoclonal detection antibody to create a sandwich ELISA specific for GLP-19–36/7.ResultsThe sandwich ELISA was highly specific for GLP-19–36/7 and did not recognize GLP-17–36 or GLP-17–37. The ELISA exhibited a broad dynamic range and a lower limit of detection (LLOD) of 3.17 ng/L. In healthy volunteers, concentrations of GLP-19–36/7 increased dramatically in the postprandial state compared to the fasted state and were markedly elevated at both 30 and 120-minute postprandial time points.ConclusionsThe optimization of an N-terminal-specific monoclonal antibody for GLP-19–36/7 enabled the development of a sensitive and specific sandwich ELISA assay capable of measuring physiological concentrations of GLP-19–36/7. This ELISA may have the potential to help expand our knowledge of GLP-1 biology.