ABSTRACT
Macrophages, and Dendritic Cells .................................................................................... 406 27.5 Role of Galectins in Neutrophil-Mediated In ammatory Responses ............................... 407 27.6 Role of Galectins in Eosinophil and Mast Cell Functions ................................................ 408 27.7 Experimental Models Used to Explore the Role of Galectins in Vivo .............................. 408 27.7.1 Galectins in the Regulation of Th1-Mediated
Autoimmunity and Chronic In ammation .......................................................... 408 27.7.2 Galectins in the Regulation of Th2-Mediated Allergic Disorders ...................... 410 27.7.3 Galectins in Tumor Immunity............................................................................... 410 27.8 Conclusion and Future Directions ..................................................................................... 410 Acknowledgments ........................................................................................................................ 411 References .................................................................................................................................... 412
Galectins are a family of highly conserved glycan-binding proteins with af nity for β-galactosidecontaining oligosaccharides [1,2]. Since the discovery of discoidin-1 in the cellular slime mold Dictyostelium discoideum [3] and electrolectin in the electric organ tissue of the electric eel [4], the family of galectins has received increasing attention. However, it was only in the 1990s that experimental evidence emerged, illuminating a role for galectins in the regulation of physiological and pathological processes, particularly in the control of immune cell homeostasis and in ammation [5]. Members of the galectin family are de ned by a conserved carbohydrate recognition domain (CRD) with a canonical amino acid sequence and af nity for β-galactosides [2,6]. To date, 15 mammalian galectins have
been identi ed, which can be subdivided into those that have one CRD (prototype) and those that have two CRDs in tandem (tandem-repeat type). In addition, galectin-3, a one-CRD galectin, is unique in that it contains unusual tandem repeats of short amino acid stretches fused onto the CRD (chimera-type) [2,7]. Many galectins bind carbohydrate moieties in a bivalent or multivalent manner. Some one-CRD galectins exist as dimers; two-CRD galectins have two carbohydratebinding sites, and galectin-3 forms oligomers when it binds to multivalent carbohydrates [8]. Galectin-mediated cross-linking of cell surface glycoconjugates can trigger a cascade of transmembrane signaling and modulate processes that include apoptosis, cytokine secretion, cell adhesion, and migration [8].
