Galectin-3, a beta-galactoside-binding animal lectin, is a marker of anaplastic large-cell lymphoma.

Galectin-3 is a member of a newly named family of beta-galactoside-binding animal lectins, which has been described with a number of possible important biological functions, including the regulation of cell growth and association with tumor transformation. This protein has a wide tissue distribution but is notably not expressed by normal lymphocytes. We have previously shown that galectin-3 is markedly up-regulated in HTLV-I-infected T cells, most likely mediated by the viral transactivating protein Tax. In this study, we surveyed various lymphomas by immunohistochemistry and found the expression of galectin-3 in all of the 8 cases of Ki-1+ anaplastic large-cell lymphoma (ALCL). Immunoreactivity for galectin-3 was found in a majority of the neoplastic cells in the ALCLs studied. In contrast, only 2 of the 35 cases of other types of lymphoma, including various Hodgkin's and non-Hodgkin's lymphomas, were positive. Unlike the cases of ALCL, immunoreactivity for galectin-3 in these 3 cases was found only sporadically in a small number of neoplastic cells. Thus, galectin-3 may prove to be a useful marker for ALCL and its expression in neoplastic cells in ALCL may contribute to the biological behavior of this specific type of lymphoma.