CD4/CD8 ratio during natalizumab treatment in multiple sclerosis patients.

Although improved, the risk of progressive multifocal leukoencephalopathy is a constant threat for patient affected by multiple sclerosis treated with natalizumab. We performed a 24months longitudinal study aimed to evaluate the total WBC and lymphocytes subsets modifications and their correlations with anti-JCV antibody index after 1 and 2years of natalizumab treatment. Natalizumab induced an increase of WBC, total and C19+ lymphocytes together with a decrease of CD3+, CD4+ T lymphocytes and CD4/CD8 ratio, which was positively related to anti-JCV antibodies index at month 0, 12 and 24. Our study confirms that lymphocytes subsets are modified under NAT therapy. Implications of lymphocyte subsets alterations in the pathogenesis of PML are under analyses.