Anti-GM1 and anti-sulfatide antibodies in polyneuropathies - Threshold titers and accuracy

Objectives - To determine threshold titers and diagnostic accuracy of anti- GM1 and anti-sulfatide antibodies (Ab) for autoimmune polyneuropathies (PN) in overall and for particular subtypes of them. Materials and methods - In this study 84 PN patients, 120 epileptics and 93 healthy controls' sera we re tested. by enzyme-linked immunosorbent assay for autoAbs and results con firmed by thin-layer chromatography. Frequencies of positive patients at in creasing cut-off were compared to determine threshold titers. Accuracy was determined by Receiver Operator Characteristic analysis. Results - A 1:2000 titer for IgM anti-GM1 and a 1:4000 titer for IgM anti-sulfatide Ab result ed to be threshold titers for autoimmune PN in overall. IgM anti-GM1 and an ti-sulfatide Ab had low discriminating capacity between autoimmune PN and o ther PN, but good discriminating capacity between motor neuropathy (for ant i-GM1 Ab) or PN in IgM-paraproteinemia or chronic painful sensory axonal PN (for anti-sulfatide Ab) and other PN. Conclusion - Our results suggest tha t testing IgM anti-GM1 or anti-sulfatide Ab is useful only for diagnostic c onfirmation of specific subtypes of autoimmune PN.