Investigation of the idiotypic determinants of IgM monoclonal proteins associated with neuropathy.

Occasionally IgM monoclonal proteins (MP) from benign gammopathies bind neural antigens and have been associated with demyelinating peripheral neuropathy. A monoclonal antibody (McAb) has been raised against a cross-reactive idiotypic determinant expressed by three out of 12 MP with specificity for neural antigens. The determinant recognised by this MoAb is only expressed when both H and L chain are properly associated. The idiotypic determinant was not expressed by 130 MP randomly selected from patients without neuropathy nor in polyclonal immunoglobulin preparations obtained from healthy individuals.