Hypersialylated macromolecular serum immunoglobulin Al in type 2 diabetes mellitus

Objectives: The origin of the elevation of serum immunoglobulin Al (IgAl) i n Type 2 diabetes mellitus (DM) is unsettled. The aim of this study was to address the carbohydrate changes of serum IgAl from patients with Type 2 di abetes mellitus, as a possible cause of the elevation. Design and methods: IgAl was purified from sera of 6 DM patients and 4 heal thy matched controls by using highly acetylated-Sepharose 6B, anti-Iga-agar ose, acid jacalin-agarose columns, and further separated into jacalin low-a ffinity, medium, and high-affinity fractions. Hinge and Fc fragments from n ative IgAl were obtained and analyzed by using Sambucus nigra, Maackia amur ensis, Arachis hypogaea, Erythrina cristagalli, and Ricinus communis lectin s. Results: The jacalin high-affinity fraction, mostly constituted by macromol ecular IgAl, was more abundant in DM patients than in controls and also mor e reactive to Sambucus nigra, and Maackia amurensis lectins. Conclusions: Macromolecular serum IgAl from DM patients is hypersialylated and this probably contributes to the high level of IgAl in DM patients. (C) 2001 The Canadian Society of Clinical Chemists. All rights reserved.