Association of variability in antibody binding affinity with a clinical course of anti-MAG neuropathy.

Anti-myelin-associated glycoprotein (MAG) neuropathy is mediated by the binding of IgM M-proteins to the human natural killer-1 epitope of several glycoconjugates, including MAG and phosphacan. We recently reported that IgM M-proteins with a higher ratio of anti-phosphacan titer to anti-MAG titer (P/M ratio) were associated with a progressive clinical course. Herein, we investigated the temporal variability of the P/M ratio. The results showed that P/M ratios in worsened cases were significantly increased relative to stable or improved cases. Thus, temporal variability in the specificity of IgM M-proteins may be related to the disease course of anti-MAG neuropathy.