Lectin histochemistry in colorectal polyps

Lectin histochemistry has permitted an assessment of the glycoconjugate expression in colorectal polyps (Table 8). The T-antigen, a cancer-associated antigen, is expressed in colorectal adenomatous polyps. The apparent expression of T-antigen is related to the methodology used for its detection. FITC-PNA does not bind to glycoconjugates in the normal colon, however it is a sensitive marker for glycoconjugates secreted by colorectal cancers. The binding of FITC-PNA in adenomatous polyps is related to size and histology. The use of biotinylated PNA (followed by avidin-biotin-peroxidase) or PNA:anti-PNA is a more sensitive technique, and the result is that binding may be seen in the normal colon as well as most neoplastic lesions. The use of polyclonal and monoclonal antibodies to the T-antigen are more specific than the PNA:anti-PNA technique. Binding of PAb and MAb anti-T-antigen to colorectal polyps is related to the size of the polyp for both probes, and binding is also related to the degree of dysplasia for the MAb. The future of this work may be directed at an attempt to determine whether a family of closely related antigens are expressed in colorectal neoplasia with varying degrees of affinity for different probes of the T-antigen.