Monoclonal IgM cold agglutinins with anti-Pr1d specificity in a patient with peripheral neuropathy.

A patient with a demyelinating sensory motor polyneuropathy secondary to IgM paraproteinaemia is reported. The paraprotein binds to the gangliosides GD1b, GT1b, GQ1b and GD3, all of which contain disialosyl groups with the sequence NeuAc alpha 2-8NeuAc alpha 2-3Gal. The paraprotein also acts as a cold agglutinin recognising the sialic-acid-dependent Pr1d antigenic determinant of the red cell membrane glycophorins. In this and in similar cases that have been reported, the coexistence of anti-Pr cold agglutinins and peripheral neuropathy suggest that they might be the causative agents of the disease.