Cytokine Variations in Monoclonal Gammopathy-Associated Polyneuropathy

Individuals with anti-myelin-associated glycoprotein (MAG) neuropathy and those with immunoglobulin M monoclonal gammopathy-associated polyneuropathy (IgM-PNP) have different median serum concentrations of interleukin 6 (IL-6) and 10 (IL-10) compared with controls, according to a study recently published in Muscle & Nerve.

This study included 81 individuals with IgM-PNP from a prospective previously reported on cohort, as well as 113 healthy controls matched for sex and age and 110 individuals with probable multifocal motor neuropathy (MMN). Sera was collected from all participants to test for the association between IgM-PNP and 11 B-cell-stimulating cytokines.

Disease severity in participants with IgM-PNP was assessed 3 years after onset using clinical and functional scores (using the INCAT Overall Disability Severity Scale). Clinical and functional scores were compared with blood sample collection and 2-year follow-up visits to examine progression speed. Rituximab responsiveness was defined as an improved functional score at the 1-year mark.

Individuals with IgM-PNP had higher median serum concentrations of IL-6, while those with IgM-PNP and anti-MAG IgM antibodies had higher concentrations of IL-10. Of the 110 participants with MMN, there were no significant increases in IL-6 or IL-10. The majority of participants with both IgM-PNP and anti-MAG neuropathy had normal IL-6 and IL-10 concentrations. Rituximab responsiveness, B-cell activating factor, and IL-6 and IL-10 concentrations did not show associations with one another.

The study researchers conclude that “patients with IgM-PNP had higher median IL-6 concentrations in serum compared with healthy controls and patients with MMN, whereas patients with IgM-PNP and anti-MAG antibodies (anti-MAG neuropathy) also had elevated median IL-10 concentrations. Immunoglobulin M monoclonal gammopathy-associated polyneuropathy is heterogeneous both in clinical characteristics and in response to treatment, and IL-6 and IL-10 serum concentrations might help in identifying subsets of patients sharing pathophysiological pathways or susceptibility to treatment.”

Reference

Stork ACJ, Rijkers GT, Vlam L, et al. Serum cytokine patterns in immunoglobulin m monoclonal gammopathy‐associated polyneuropathy [published online March 7, 2019]. Muscle Nerve. doi:10.1002/mus.26462