Basic studies on a labeled anti-mucin antibody detectable by infrared-fluorescence endoscopy

Background. We developed a fluorescent dye, indocyanine green (ICG)-sulfo-OSu, which was excited by infrared rays and conjugated to various antibodies. We attempted to clarify the staining patterns of anti-sulfomucin and anti-MUC1 antibodies in gastrointestinal cancer. We then evaluated the potential of the dye as a fluorescent label for antibodies specific to cancer, to be used as a diagnostic method for microcancer, with infrared fluorescence endoscopy. Methods. Paraffin sections of samples collected from 10 patients with esophageal cancer, 30 patients with gastric cancer, and 20 patients with colorectal cancer were immunohistologically stained using an anti-sulfomucin antibody and an anti-MUC1 antibody, and the staining patterns were examined. If a section had a high staining intensity, it was reacted with the ICG-suflo-OSu-labeled antibody and evaluated with infrared fluorescence imaging. Results. The staining patterns with the antibodies varied depending on the organs and the histological types and depth of the cancers, but the staining was generally good and the staining on the mucosal surface of cancer tissues was retained. Good images of cancer cells could be obtained by infrared fluorescence observation using the ICG-sulfo-OSu-labeled anti-MUC1 antibody. Conclusions. The anti-MUC1 antibody stained gastrointestinal cancer cells well, and nearly specific infrared fluorescence in cancer tissues was observed using the labeled anti-MUC1 antibody. The ICG-sulfo-OSu-labeled anti-MUC1 antibody has possible usefulness for the screening of cancer via infrared fluorescence endoscopy. Received: December 8, 2000 / Accepted: September 28, 2001