The Thomsen-Friedenreich (TF) antigen: a critical review on the structural, biosynthetic and histochemical aspects of a pancarcinoma-associated antigen.

Within the family of blood-group related carbohydrate antigens the Thomsen-Friedenreich (TF) antigen (or T antigen) is an outstanding member by attracting scientific interest for more than 65 years and by having retained its significance as object of current biomedical research; in particular, as a pancarcinoma-associated antigen. In accordance with its constant or even growing attraction scientists have searched for specific reagents which would allow the unambiguous and sensitive detection of the Thomsen-Friedenreich antigen on cells or tissues. While at the beginning, immunohistochemical work on TF antigen expression was restricted by the limited specificity of plant lectins (peanut lectin) a significant progress has been possible since the introduction of the hybridoma technique. The respective monoclonal antibodies display distinct fine specificities and cellular staining patterns in immunohistochemistry and have contributed to controversial discussions on the organ-characteristic and tumor-associated expression of the TF antigen in some organs. It is the aim of this survey to summarize in the context of its structural and biosynthetic aspects the current knowledge on the tissue expression of the TF antigen as based on the use of peanut agglutinin and monoclonal antibodies and to discuss the findings with regard to their biomedical relevance, in particular, with emphasis on their value in tumor diagnosis.