A SENSITIVE SANDWICH ELISA FOR MEASURING THROMBOPOIETIN IN HUMAN SERUM - SERUM THROMBOPOIETIN LEVELS IN HEALTHY-VOLUNTEERS AND IN PATIENTS WITH HEMATOPOIETIC DISORDERS

A sensitive sandwich enzyme-linked immunosorbent assay (ELISA) has bee n established to estimate serum thrombopoietin (TPO) concentrations in healthy volunteers and patients with haemopoietic disorders. The ELIS A uses a mouse monoclonal antibody (Ab) as the capture Ab and a biotin ylated rabbit polyclonal Ab as the detector. The ELISA was reproducibl e, highly sensitive and specific for human TPO. The coefficients of in tra- and interassay variation were from 3.0% to 4.9% and from 5.9% to 6.1%, respectively. The quantitative limit of the ELISA was 0.09 fmol/ ml in serum. The quantitative limit was lower than the normal level. T he dose-response curves of serum samples from healthy volunteers and p atients with haemopoietic disorders were parallel to the standard curv es. The ELISA did not cross-react with a variety of blood components a nd cytokines to produce false-positive results. The serum TPO concentr ations from 29 normal males and 21 females were 0.79 +/- 0.35 and 0.70 +/- 0.26 fmol/ml, respectively. Serum TPO levels in patients with apl astic anaemia (AA). acute lymphocytic leukaemia (ALL) and essential th rombocythaemia (ET) were measured using the ELISA. The serum TPO level s in the patients with ET (n = 6, 2.80 +/- 1.55 fmol/ml) were higher t han the normal level. The patients with AA (n = 7, 18.53 +/- 12.37 fmo l/ml) and ALL (n = 5, 10.36 +/- 5.57 fmol/ml) had significantly higher serum TPO levels than normal individuals. These results indicate that the ELISA specific to TPO should prone useful in measuring the TPO co ncentration in serum samples.