A sensitive enzyme immunoassay system for the measurement of beta-thromboglobulin in plasma and urine

A sensitive enzyme immunoassay system for the measurement of beta-thromboglobulin (beta-TG) in plasma and urine was developed using purified antibodies to beta-TG linked to beta-D-galactosidase from Escherichia coli as label. The assay system consisted of polystyrene beads with immobilized antibody F(ab')2 fragments and the antibody Fab' fragments labeled with beta-D-galactosidase. The assay had a sensitivity of 10 pg/assay tube. beta-TG levels in plasma and urine could be determined with 1-2.5 microliters and 100 microliters samples, respectively. The results obtained with the enzyme immunoassay correlated well with those of a radioimmunoassay (r = 0.946, slope = 0.846, y-intercept = 4.71 ng/ml; n = 60). Plasma beta-TG levels in healthy subjects determined with the present assay system were 38.4 +/- 12.2 ng/ml (+/- 1 SD). Levels were markedly increased in 19 out of 22 patients with myeloproliferative syndrome. Urinary beta-TG levels in healthy subjects were estimated to be 0.17 +/- 0.05 ng/ml (+/- 1 SD). Urine levels were increased in 16 out of the 19 patients with myeloproliferative syndrome whose plasma levels were high. These findings indicate that urinary beta-TG levels may be reflection of the beta-TG in plasma and can be an indicator of platelet activation.