TAG-72

The tumor-associated glycoprotein 72 (TAG-72) is a glycoprotein related to the sialyted Tn antigen and is frequently expressed in a variety of adenocarcinomas. It is a membrane mucin-like protein and its molecular weight is approximately 220-400kD. Initially, the tumor-associated glycoprotein-72 has been identified using monoclonal antibody (MAb) B72.3. TAG-72 could bind to endocytic receptors on DCs that contain sugar binding domains. The mannose receptor has eight extracellular C-type lectin-like domains (CTLDs) of which four or five bind to multiple ligands containing mannose, fucose or N-acetyl glucosamine.
It has a very limited expression pattern in the majority of normal adult tissues with the exception of the secretory endometrium. It has been demonstrated that TAG-72 is not expressed in neural tumors or in adult normal tissues except in secretory endometrium; however, its expression was detected in certain fetal tissues. Thus, the fact that TAG-72 is positive in many adenocarcinomas while lacking a significant reactivity with normal tissues suggests the potential diagnostic and therapeutic utility for human carcinomas and has been widely investigated. The mAb B72.3, which is directed against TAG-72, is associated with 95% overall recognition for adenocarcinomas on paraffin-embedded effusions, particularly those with origin in the lung, whereas reactive mesothelial cells are negative.