Peripheral neuropathy associated with monoclonal IgM anti-Pr2 cold agglutinins

A patient with a chronic, large fibre sensory neuropathy had an immunoglobulin M lambda monoclonal paraprotein reactive at titres in excess of 1/10(5) with NeuNAc(alpha 2-8)NeuNAc(alpha 2-3)Gal configured disialosyl groups present on the gangliosides GD1b, GT1b, GQ1b, and GD3. The paraprotein showed weaker reactivity with GD1a, GM3, and LM1 but no reactivity with GM2, GM1, or asialo-GM1. In addition, the paraprotein had cold agglutinating activity with anti-Pr2 specificity, Pr2 being an antigenic determinant on membrane glycoproteins or glycolipids in erythrocytes or both. A large fibre sensory neuropathy with monoclonal anti-disialosyl antibodies is an increasingly recognised form of paraproteinaemic neuropathy.