An enzyme-linked immunosorbent assay (ELISA) for adenosine 3',5'-cyclic monophosphate (cAMP) in human plasma and urine using monoclonal antibody.

A reliable and sensitive ELISA for cAMP in human plasma and urine is described, using a monoclonal antibody and a 96 well microtiter plate. Succinyl cAMP is conjugated to human serum albumin and adsorbed to the ELISA plate, giving an immobilized antigen approach which simplifies subsequent assay procedures. As low as 1.56 fmol/well of both plasma and urinary cAMP is measurable. Recoveries of added cAMP in plasma and urine were from 99% to 109%. Intra-assay coefficients of variation were less than 6.1% for plasma and 7.0% for urine samples. Inter-assay coefficients of variation for plasma and urine samples were less than 8.9% and 9.5%, respectively. There was a good correlation between the values obtained by ELISA and radioimmunoassay (RIA) (plasma: r = 0.94, n = 66; urine: r = 0.98, n = 64; nephrogenous cAMP: r = 0.96, n = 51).