Coexpression of binding sites for A(B) histo-blood group trisaccharides with galectin-3 and Lag antigen in human Langerhans cells

Galectin-3 is an immunomodulatory protein with binding capacity for various glycoconjugates including IgE, It has been shown to be produced by epiderm al keratinocytes and is present on the surfaces of skin Langerhans cells (L C), Therefore, it may have a role in the pathogenesis of various skin disea ses, such as atopic dermatitis. To study the expression of galectin-3 in LC , we used, in addition to specific antibodies, a panel of synthetic, carrie r-immobilized, specific oligosaccharides of the A- and B-histo-blood group, which are recognized by this lectin, In the mean time, Birbeck granules we re visualized with an anti-Lag antibody. The double labeling experiments sh owed a remarkable colocalization of signals for Lag antigen (Birbeck granul es) and galectin-3, as well as the binding sites for A- and B-histo-blood g roup trisaccharides. The specificity of the oligosaccharide binding Tvas de monstrated by the lack of binding by Le(c), Le(d) (H blood group antigen), and sLe(x), which are mt recognized by galectin-3, These results suggest th at galectin-3 is present in Birbeck granules, where it retains reactivity f or its glycoligands.