Heterogeneity of human anti-MAG IgM as revealed by their reactivity on avian embryonic tissues.

Monoclonal IgM from patients with peripheral neuropathies frequently have an antibody activity directed against myelin-associated glycoprotein (MAG). Reactivity of 19 of these sera with avian embryonic tissues was compared. Immunohistological studies allowed their classification into distinct groups according to the staining pattern. Both neural and non-neural cell lineages were recognized by these antibodies. The IgM specificities were also compared with those of the monoclonal antibodies HNK-1 and NC-1, which react with MAG and some cell adhesion molecules. Only one group displayed a pattern of staining similar to that observed with these monoclonals. The reactivity of these IgM paraproteins with two cell adhesion molecules, neural cell adhesion molecule and neuron-glia-cell adhesion molecule by immunoblotting confirmed the heterogeneity found in the histological study.