AN ANTIBODY-LECTIN SANDWICH ASSAY FOR THE DETERMINATION OF CA125 ANTIGEN IN OVARIAN-CANCER PATIENTS

A two-step forward sandwich assay was developed for the determination of the ovarian tumour associated glycoconjugate antigen CA125 with ant i-CA125 Monoclonal antibody B27.1 on the solid phase and I-125-labelle d wheat germ lectin as tracer in the solution phase. This Mab-lectin h eterosandwich assay was optimized and the clinical utility was evaluat ed in sera from healthy volunteers and ovarian cancer patients. A corr elation was established between Mab-lectin assay and the dual monoclon al antibody sandwich assay, TRUQUANT(R)OV2 RIA, that uses the same MAb B27.1 on the solid phase and a second I-125-labelled B43.13 MAb in th e solution phase. A potentially improved clinical utility is suggested for the Mab-lectin assay. The unique format seems to identify novel i soforms of CA125 with different carbohydrate side chains that would ot herwise be undetectable in the MAb-MAb sandwich assay wherein the para topes are likely directed to protein determinants.