Determination of serum tetranectin: technical and clinical evaluation of three sandwich immunoassays

The performance of two sandwich-type immunoassays for the determination of the tumour marker tetranectin using monoclonal antibodies Hyb 130-13 and 130-14 as catching layer was compared with the performance of a polyclonal assay. Sensitivities were 0.4-0.6 microg/l, and intra- and inter-assay coefficients of variation were < 10% in all assays. One-hundred-and-ten blood donors were examined, and women had higher concentrations of tetranectin in serum than men when measured with monoclonal assays (P < 0.05). In preoperative serum samples from 43 patients with ovarian cancer, tetranectin concentrations were reduced (P < 0.001), and the mean tetranectin concentration decreased with increasing FIGO stage of the patients (P < 0.05). In sera from patients with ovarian cancer, tetranectin concentrations were lower in the polyclonal assay than in the monoclonal assays. This could, hypothetically, be explained by ligand-binding or other conformational changes in tetranectin, influencing the antigenicity of the molecule.