Objective    To produce monoclonal antibodies against colorectal carcinoma and provide a new tool for study of the mechanisms in related cancers.     Methods    Specimens of colorectal carcinoma were freshly obtained from surgery. Balb/c mice were immunized with cell suspension from colorectal carcinoma tissues. Fusion was done as classical hybridoma method. Positive hybridomas were selected by immunohistochemical staining. The nature and biological characteristic of the selected monoclonal antibodies was investigated.     Results    Thirty-two positive hybridomas were selected. Two (2-3

15-8) of these hybridomas secreted antibodies binding specifically to human colorectal carcinoma. By immunohistochemical staining

all of colorectal carcinoma cases was positive for 2-3 antibody. In contrast

normal colon and rectal mucosa showed much weaker staining

and was totally negative when 2-3 ascites antibody was diluted over 1∶6 000. In addition

2-3 antibody reacted strongly with moderately differentiated and poorly differentiated colorectal carcinoma. The immunoreactive substance was observed on luminal contents of colorectal carcinoma tubules and on apical surface of normal epithelium

indicating that the antigen recognized by 2-3 antibody may be a kind of mucin secreted by colorectal carcinoma and normal epithelium and may participate in tumor invasion and metastasis.     Conclusion    We successfully produced two monoclonal antibodies against colorectal carcinoma.