Galectin-3 is a beta-galactoside-binding lectin with a molecular weight of 31 kDa. It has been found to interact with the basement membrane glycoprotein laminin. Galectin-3 is normally present in the epithelial cells of various organs and is also found in inflammatory cells such as macrophages, dendritic cells, and Kupffer cells. Its expression is up-regulated during inflammation, cell proliferation, cell differentiation, and can be induced by viral proteins.

The galectin-3 antibody has proven to be valuable in distinguishing between benign and malignant thyroid neoplasms, both in histologic sections and in fine-needle aspiration biopsy material. By using the galectin-3 antibody, it is possible to differentiate between different types of thyroid tumors based on their immunoreactivity. Additionally, the galectin-3 antibody has been useful in identifying anaplastic large cell lymphoma.