Anti-sulfatide IgM antibodies in peripheral neuropathy: to test or not to test?

Background and purpose Anti-sulfatide immunoglobulin M (IgM) antibodies have been associated with different forms of neuropathies but their diagnostic role in neuropathy remains unclear. Methods The clinical association of increased titers of anti-sulfatide IgM antibodies in 570 patients with neuropathy and related disorders examined in our laboratory since 2004 was reviewed. Sera were tested by enzyme-linked immunosorbent assay at the initial serum dilution of 1:32 000 and titrated by serial two-fold dilution. In all positive patients IgM antibodies to myelin-associated glycoprotein (MAG) were also measured by western blot. Results High titers of anti-sulfatide antibodies were found in 39 patients including 33 (85%) who also had anti-MAG IgM. Six patients did not have anti-MAG IgM including five in whom moderately increased anti-sulfatide titers were associated with different forms of neuropathy. One patient with a demyelinating neuropathy and IgM monoclonal gammopathy had markedly increased anti-sulfatide titers (1:256 000). Conclusions Increased titers of anti-sulfatide IgM antibodies are not infrequent in patients with neuropathy where they are often associated with a concomitant reactivity to MAG. A selective reactivity to sulfatide, however, is rarely found and is associated with different forms of neuropathy limiting its usefulness in the diagnosis of neuropathy.