Evaluation of an enzyme-linked immunosorbent Raji cell assay (ELISA) in the investigation of gastrointestinal cancer.

The levels of circulating immune complexes (CICs) have been estimated in a group of patients with colorectal cancer and gastric cancer, in addition to which a normal range has been established in a group of patients with benign gastrointestinal disease. A newly developed enzyme-linked immunosorbent Raji cell assay has been used in this study. Overall only 30% of patients with gastrointestinal cancer showed elevation of CIC levels outside the normal range. Elevated levels correlated with tumour differentiation bud did not correlate with site of disease or with the presence of metastases. In an attempt to define the specificity of CIC estimation, soluble tumour extract was added to sera from tumour-bearing patients. Specific IC elevations were produced by addition of allogeneic tumour extract of colon cancer in patients with colorectal cancer; this phenomenon was not seen when the same extract was added to the sera of patients with gastric cancer.