Detailed Structure and Pathophysiological Roles of the IgA-Albumin Complex in Multiple Myeloma

Therapeutic plasma exchange for hyperviscosity syndrome in IgA multiple myeloma

Hyperviscosity syndrome (HVS) is defined as the symptomatic presentation of increased blood thickness due to various clinical conditions such as hypergammaglobulinemia. HVS secondary to immunoglobulin (Ig)A multiple myeloma has been infrequently reported. Although the efficiency of IgM or IgG removal by therapeutic plasma exchange (TPE) is well described, the efficiency of IgA removal by TPE is not as well known. Here, we describe a case of HVS due to IgA myeloma in a patient who received 2 TPE treatments, with subsequent symptomatic improvement as well as decrease in IgA and viscosity levels.

Proteins in human body fluids contain in vivo antigen analog of the melibiose-derived glycation product: MAGE

Melibiose-derived AGE (MAGE) is an advanced glycation end-product formed in vitro in anhydrous conditions on proteins and protein-free amino acids during glycation with melibiose. Our previous studies revealed the presence of MAGE antigen in the human body and tissues of several other species, including muscles, fat, extracellular matrix, and blood. MAGE is also antigenic and induces generation of anti-MAGE antibody. The aim of this paper was to identify the proteins modified by MAGE present in human body fluids, such as serum, plasma, and peritoneal fluids. The protein-bound MAGE formed in vivo has been isolated from human blood using affinity chromatography on the resin with an immobilized anti-MAGE monoclonal antibody. Using mass spectrometry and immunochemistry it has been established that MAGE epitope is present on several human blood proteins including serum albumin, IgG, and IgA. In serum of diabetic patients, mainly the albumin and IgG were modified by MAGE, while in healthy subjects IgG and IgA carried this modification, suggesting the novel AGE can impact protein structure, contribute to auto-immunogenicity, and affect function of immunoglobulins. Some proteins in peritoneal fluid from cancer patients modified with MAGE were also observed and it indicates a potential role of MAGE in cancer.