Direct ELISA method for the specific determination of prothymosin alpha in human specimens.

An enzyme linked immunosorbent assay, specific for prothymosin alpha (ProT alpha) was developed using an antibody against the synthetic C-terminal peptide ProT alpha[101-109] and isolated bovine ProT alpha for the preparation of standard solutions and immunoplates. Due to the antibody used, the ELISA developed was capable of fully discriminating between ProT alpha, the naturally occuring and partially homologous peptide parathymosin alpha (ParaT alpha) and the peptide thymosin alpha1 (T alpha1), whose sequence is identical to the [1-28] sequence of ProT alpha, and its in vivo occurrence is under question. Moreover, due to its improved sensitivity, the ELISA was capable of directly determining ProT alpha concentration in human serum and tissue extracts, without any pretreatment of the samples. ProT alpha 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 microg/ml (mean value 1.27 +/- 0.49 microg/ml) and from 0.47 to 1.74 microg/ml (mean value 1.02 +/- 0.29 microg/ml), respectively. ProT alpha levels were also measured in four breast tumor and adjacent normal breast tissue extracts and found to be elevated in the tumor extracts.