Possible Role of Human Natural Anti-Gal Antibodies in the Natural Antitumor Defense System

Abstract

Expression of Galα1–3Gal cell surface residues has been correlated with the metastatic potential of murine tumor cells. We report that Galαl–3Gal residues are expressed at the cell surface of malignant human cancer cells, including four cell lines and 50% of the malignant breast specimens obtained by aspiration biopsy. In contrast, all benign breast biopsies and normal cells were Galα1–3Gal negative. Affinity-purified anti-α-galactosyl IgG (anti-Gal) antibody, which specifically recognizes Galα1–3Gal residues, significantly inhibited cell attachment in two in vitro assays thought to indicate tumor cell extravasation of the circulatory system during the metastatic process: attachment to perfused human umbilical vein endothelium, and attachment to isolated laminin. Since anti-Gal antibody is a natural component of all human sera, we propose that it may be part of the natural antitumor defense system in humans. [J Natl Cancer Inst 1989;81:212–216]