Sera from children with Type 1 diabetes mellitus react against a new groupof antigens composed of lysophospholipids

Several autoantibodies related to Type 1 diabetes mellitus and their corres ponding autoantigens have been previously identified. While peptide antigen s are more widely recognized, lipid antigens like sulfatides and gangliosid es are also known epitopes for the diabetic humoral immune response. Islet cell antibodies (ICA) in Type 1 diabetes are heterogeneous immunoglobulins directed against selected antigens in the islets of Langerhans, Moreover, I CA may be the best predictive marker of disease in family members of patien ts with Type 1 diabetes. The aims of this study were: (1) to purify lipids from porcine pancreas that contain ICA epitopes; (2) to characterize these lipid antigens, and (3) to use the purified lipids in an assay to detect an tibodies in patients with Type 1 diabetes. A unique family of 4 lysophospho - lipids, 1 fully characterized as lysophosphatidylmyoinositol, partially i nhibited ICA staining, and therefore, were considered to be candidate antig ens for an ICA immunoassay. Using a dot blot immunoassay, we detected antib odies directed against these phospholipids in 28 out of 46 (61%) diabetic s era, while detecting only 1 false positive out of 28 nondiabetic sera (3.6% ; p < 0.0001 comparing diabetic vs. nondiabetic serum). Therefore, lysophos pholipid immunoassay positivity is present in sera of Type 1 diabetic patie nts. Furthermore, we detected 15 out of 23 ICA-negative diabetic sera (65.2 %), showing that our phospholipid immunoassay does not correlate with ICA p ositivity. Copyright (C) 2000 S. Karger AG, Basel.