Antibodies in normal rabbit serum that react with tissue-specific antigens on the plasma membranes of human adenocarcinoma cells.

Indirect viable cell immunofluorescence studies revealed, on the plasma membrane of cultured adenocarcinoma cells from the human colon and rectum, a tissue-specific antigen that reacted with a component of normal rabbit serum. The use of G200 column chromatography and monospecific antisera prepared against class-specific heavy chains of rabbit immunoglobulin indentified the reactive components in rabbit serum as IgM. Examination of normal and malignant cells from various human tissues by immunofluorescence and adsorption studies showed that rabbit serum reacted only with cells derived from the intestinal epithelium.