Assay of a seric human hexapeptide (HWESAS) using a monoclonal antibody and ELISA

Human serum contains low-molecular-weight growth factors potentiating some in vitro biological effects of IGF-I and IGF-II and recently two peptides w ere mainly identified: HWESAS and WGHE. In order to determine seric HWESAS concentration, a specific monoclonal antibody against HWESAS was prepared. Its specificity was studied by inhibition tests: this antibody cross-reacts with Y-HWESAS, Cys-HWESAS. It does not react with HWESAS when its COOH is blocked, or with HWE, WGHE and tryptophan or with C3f (SSKITHRIHWESASLLR) w hich is a fragment of human complement containing HWESAS motif. Its affinit y was measured by non competitive enzyme immunoassay (3.89+/-2.44 . 10(8) M -1). Then, this antibody was used in enzyme-linked immunosorbent assay (ELI SA) and the preliminary assays were performed to detect HWESAS in serum. In contrast to healthy subjects, patients with chronic renal failure exhibite d undetectable concentration off hexapeptide while after successful renal t ransplantation values increased to reach levels found in healthy subjects a nd varying according to post-operative evolution. These data are a strong h int that the kidney plays an important role in the production of this hexap eptide and underly the clinical interest of HWESAS detection in renal patho logy. (C) 2000 Elsevier Science B.V. All rights reserved.