Crypt cell antigen expression in human colon tumor cell lines: analysis with a panel of monoclonal antibodies to CaCo-2 luminal membrane components.

Twenty BALB/c mouse monoclonal antibodies to surface membrane components of confluent CaCo-2 cells were used to study the expression of small intestine markers in cultured human colon tumor cells. The antigens recognized by 15 of these antibodies were identified as membrane proteins of relatively high molecular weight, one of them corresponding to the single-chain precursor of sucrase-isomaltase. By immunofluorescence, 14 antibodies were found to stain the small intestine epithelial cells, and various distinctive patterns of antigen distribution in human jejunum were observed. Five antibodies stained exclusively the crypt cells, 3 the luminal membranes of the absorptive villus cells, and 4 the entire epithelium. In contrast, only 4 antibodies stained normal human colon tissue. The different antigens defined by this panel of monoclonal antibodies showed great variability in their expression in 14 human intestinal tumor cell lines tested. These results demonstrated a surprising similarity between many colon tumor cell lines and intestinal crypt cells and identified a set of new intestinal cell surface markers that can be used to identify and characterize intestinal tumor cells in vivo and in culture.