HISTONES AND RELATED PREPARATIONS INTERFERE WITH IMMUNOASSAYS FOR PEPTIDE-HORMONES

We report here that histones and certain related preparations generate a consistent interference with radioimmuno (RIA), immunoradiometric ( IRMA), and enzyme-linked immunosorbent (ELISA) assays for a number of peptide hormones. Histones H 1, H2A, H2B, H3, HIIA, HIIS, protamine, a nd the related preparations homeostatic thymus hormone and peptide MB3 5 generated a dose-dependent signal in both the human corticotropin-re leasing hormone (CRH) and the human adrenocorticotropic hormone (ACTH) IRMA. This signal was not affected when the linker antiserum was remo ved from the IRMA reagent mixture, thus proving that the signal was no t due to cross-reaction or sample contamination with CRH or ACTH. The above histone preparations, as well as protamine, but not ubiquitin, a lso generated a strong negative interference with RIAs for ACTH, CRH, rat growth hormone (rGH), and rat prolactin (rPRL). In an ELISA system for the thymic peptide facteur thymique serique, histones and protami ne again showed a strong interfering activity. When known amounts of r GH, rPRL, and hACTH were dissolved in charcoal-washed horse serum or s upernatants from rat liver homogenates (centrifuged 1 h at 10,000 X g) , and the corresponding RIAs and IRMA (for ACTH) were performed in the absence or presence of histones HIIA and HIIS (at 1 mg/ml level), an interfering activity of histones was again observed. We conclude that histones and some related peptide preparations have, when present in b iologic fluids, a significant capacity to interfere with peptide immun oassays.