The present invention relates to proteins which specifically bind to IgA1 and which have been modified to comprise either O- or N-linked glycans. The invention encompasses methods for decreasing IgA1, preferably abnormally glycosylated IgA1, in an individual by administering to the individual a glycan-modified IgA1 binding protein of the invention. The invention also encompasses a method for the treatment of a disease characterized by IgA1 deposition wherein a glycan-modified IgA1 binding protein is administered to an individual in need thereof.
