DETECTION OF A CIRCULATING GASTROINTESTINAL CANCER ANTIGEN IN SERA OF PATIENTS WITH GASTROINTESTINAL MALIGNANCIES BY A DOUBLE DETERMINANT IMMUNOASSAY WITH MONOCLONAL-ANTIBODIES AGAINST HUMAN-BLOOD GROUP DETERMINANTS

  • 1 January 1984
    • journal article
    • research article
    • Vol. 55  (1) , 23-35
Abstract
Monoclonal antibodies (MoAb) produced against determinants A and B of the human ABO blood group system and against the Lea and Leb determinants of the Lewis (Le) blood group system detected these determinants on molecules released by cultured cells of human colorectal, gastric and/or pancreatic carcinoma (Ca) but not by a variety of other cells maintained in culture. Circulating Le antigen could be demonstrated in sera of patients by inhibiting the binding of MoAb to a target preparation. A double deteminant radioimmunoassay (DDIA) was then devleoped to detect the association of blood group determinants with a previously defined gastrointestinal cancer antigen (GICA). The DDIA with the anti-blood group and anti-GICA antibody was in some cases more sensitive in detecting GICA in sera than using the anti-GICA MoAb alone. Of 55 sera from patients with primary and early recurrent colorectal carcinoma (CRC), 10 (18%) were scored positive in the DDIA using only anti-GICA MoAb. When MoAb binding to a determinant on Leb and on H, type I, was used as 1st antibody in DDIA followed by anti-GICA MoAb 11 additional sera were reactive, increasing the percentage of positive sera to 38. Using the same combinations of MoAb, the sensitivity of detection of GICA was only slightly improved from 63-66% in sera of patients with advanced CRC. The number of false positive sera from patients with non-malignant gastrointestinal diseases or from healthy donors remained at low levels when anti-blood group determinant antibodies were used together with anti-GICA MoAB. DDIA with MoAb against different blood group determinants and tumor associated antigens can improve the detection of circulating antigens in patients with early stage cancer.