The contribution of coctail of two monoclonal antibodies, anti-CEA and anti-CA 19-9, for the enhancement of antibody binding in tumor tissue comparing to single antibody was investigated immunohistologically in 101 colorectal adenocarcinomas. Sixty nine percent of were homogeneously positive for CEA, thirty percent heterogeneously positive and only one case was negative. The CA 19-9 antigen expression was homogeneous in 13%, heterogenous in 67% and the rest was negative. The mixture of both antibodies contributed at least in 30% to increased number of bindings in tumor tissue and even in 80% if also the increase of bindings per cell is taken into the account. However in many tumors with heterogeneous expression of both antigens the substantial portion of tumor cells remained negative which seems to be the main limitation for effective immunotargeting in some cases using simple cocktail of antibodies.
Coexpression of CEA and CA 19-9 in patients with colorectal carcinoma
