Direct ELISA Method for the Specific Determination of Prothymosin Alpha in Human Specimens

Abstract

An enzyme linked immunosorbent assay, specific for prothymosin alpha (ProTα) was developed using an antibody against the synthetic C-terminal peptide ProTα[101–109] and isolated bovine ProTα for the preparation of standard solutions and immunoplates. Due to the antibody used, the ELISA developed was capable of fully discriminating between ProTα, the naturally occuring and partially homologous peptide parathymosin alpha (ParaTα) and the peptide thymosin α1 (Tα1), whose sequence is identical to the [1–28] sequence of ProTα, and its in vivo occurrence is under question. Moreover, due to its improved sensitivity, the ELISA was capable of directly determining ProTα concentration in human serum and tissue extracts, without any pretreatment of the samples. ProTα levels were directly measured in sera obtained from 48 apparently healthy individuals and 27 patients with diagnosed breast cancer and found to range from 0.67 to 2.34 μg/ml (mean value 1.27 ± 0.49 μg/ml) and from 0.47 to 1.74 μg/ml (mean value 1.02 ± 0.29 μg/ml), respectively. ProTα levels were also measured in four breast tumor and adjacent normal breast tissue extracts and found to be elevated in the tumor extracts.