Sural nerve T cells in demyelinating polyneuropathy associated with monoclonal gammopathy.

The clinical presentation of polyneuropathy associated with monoclonal gammopathy is heterogeneous. As T cells in sural nerve biopsy specimens may represent a marker of inflammation, we analyzed whether the presence of sural nerve T cells in patients with demyelinating polyneuropathy associated with monoclonal gammopathy may help to define a specific clinical entity. Using immunohistochemical analysis we investigated the number and distribution of sural nerve T cells in 18 patients with polyneuropathy associated with IgM monoclonal gammopathy (including 14 with antibodies to the myelin-associated glycoprotein) and 7 with IgG monoclonal gammopathy, and compared them with sural nerves of 23 patients with chronic inflammatory demyelinating polyneuropathy (CIDP), 15 patients with chronic idiopathic axonal polyneuropathy (CIAP), and 10 normal controls. Six patients with polyneuropathy associated with monoclonal gammopathy had increased T cell densities compared with CIAP patients and normal controls. No differences were found in distribution or phenotype of the T cells. T cell densities in patients with IgM monoclonal gammopathy were significantly lower than in patients with IgG monoclonal gammopathy or with CIDP. Increased sural nerve T cells were significantly associated with a subset of patients who had a more progressive disease course and more pronounced weakness. Increased sural nerve T cells were found significantly more often in patients with a monoclonal gammopathy of the IgG isotype, which was frequently associated with hematological malignancy.