Enzyme-linked immunosorbent assay (ELISA) for the measurement of small quantities of α₂-macroglobulin

Abstract

Munck Petersen C, VestergåRrd Povlsen J, Ingerslev J. Enzyme-linked immunosorbent assay (ELISA) for the measurement of small quantities of α₂-macro-globulin. Scand J Clin Lab Invest 1985; 45: 735–740.

A simple, sensitive and precise enzyme-linked immunosorbent assay for the quantitation of α₂-macroglobulin (α₂M) in supernatants of cell cultures was constructed. All reagents apart from the α₂M standard were commercially available. The assay range was 2.0–500 μg/1. The intra-assay coefficient of variation (CV%) was 4.6%, and the imprecision between runs was 8.9% at 10 fig/1 and 9.0% at 110 μg/1. Recovery of α₂M, added to cell culture medium free of serum, was 97.5±7.2% (mean±SD) and the recovery of α₂M added to pooled human serum was 101±6.0%. There was no significant difference between the recovery of α₂M-standard and α₂M-trypsin complexes, whereas the dose response of a commercial α₂M-standard was lower than expected (81.1±7.5%), indicating a lower purity and/or conformational changes in the epitopes of this reagent. As expected, supernatants of mononuclear lymphocyte cultures enriched in monocytes contained significantly higher concentrations of α₂M than supernatants of cell cultures depleted in monocytes. Our results indicate that the ELISA method could be a useful tool in the study of the α₂ M turnover in all cell cultures in vitro.

Key Words:

• α₂-macroglobulin
• enzyme-linked immunosorbent assay
• cell culture α₂-macroglobulin