title: Galectin-1, an endogenous lectin produced by thymic epithelial cells, induces apoptosis of human thymocytes.
abstract: Galectin-1, a beta-galactoside binding protein, is produced by thymic epithelial cells and binds to human thymocytes. We have previously reported that galectin-1 induces the apoptosis of activated T lymphocytes. Because the majority of thymocytes die via apoptosis while still within the thymus, we tested whether galectin-1 could induce the apoptosis of these cells. We now report that in vitro exposure to galectin-1 induced apoptosis of two subsets of CD4(lo) CD8(lo) thymocytes. The phenotypes of susceptible thymocytes were consistent with that of both negatively selected and nonselected cells. Galectin-1-induced apoptosis was enhanced by preexposure of thymocytes to antibody to CD3, suggesting that galectin-1 may be a participant in T-cell- receptor mediated apoptosis. In contrast, pretreatment of thymocytes with dexamethasone had no effect on galectin-1 susceptibility. We noted that 71% of the cells undergoing apoptosis after galectin-1 treatment had a DNA content greater than 2N, indicating that proliferating thymocytes were most sensitive to galectin-1. We propose that galectin-1 plays a role in the apoptosis of both negatively selected and nonselected thymocytes, and that the susceptibility of thymocytes to galectin-1 is regulated, in part, by entry or exit from the cell cycle.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of California Los Angeles School of Medicine, Los Angeles, California 90095, USA.
authors.forename: N L
authors.initials: NL
authors.lastname: Perillo
authors.forename: C H
authors.initials: CH
authors.lastname: Uittenbogaart
authors.forename: J T
authors.initials: JT
authors.lastname: Nguyen
authors.forename: L G
authors.initials: LG
authors.lastname: Baum
mesh_terms: D017209:Apoptosis; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects; D002478:Cells, Cultured; D004247:DNA / Q000032:analysis; D004229:Dithiothreitol / Q000494:pharmacology; D004848:Epithelium / Q000276:immunology; D005434:Flow Cytometry; D037483:Galectin 1; D006388:Hemagglutinins / Q000494:pharmacology* / Q000502:physiology; D006801:Humans; D037102:Lectins / Q000494:pharmacology*; D018448:Models, Immunological; D011994:Recombinant Proteins / Q000494:pharmacology; D016176:T-Lymphocyte Subsets / Q000187:drug effects* / Q000276:immunology; D013601:T-Lymphocytes / Q000187:drug effects* / Q000276:immunology; D013950:Thymus Gland / Q000276:immunology*
chemical_list: D037483:Galectin 1; D006388:Hemagglutinins; D037102:Lectins; D011994:Recombinant Proteins; D004247:DNA; D004229:Dithiothreitol