Multiplex array analysis of circulating cytokines and chemokines in natalizumab-treated patients with multiple sclerosis.

Natalizumab greatly reduces inflammatory relapses in multiple sclerosis (MS) by blocking the integrin-mediated leukocyte traffic to the brain, but less is known about its effects on the systemic immunity. We measured 48 cytokines/chemokines in sera from 19 natalizumab-treated MS patients. Serum concentrations of both anti-(IL-10, IL1ra) and pro-inflammatory (IL7, IL16) molecules decreased after 21-month treatment, without associations to unbalanced Th2/Th1cytokine ratios, clinical responses, and blood/urine replication of polyomavirus JC (JCPyV). No patient developed the JCPyV-related progressive multifocal leukoencephalopathy (PML), the major risk factor of natalizumab therapy. Our data suggest that natalizumab has marginal impact on the systemic immunity.