The varicella-zoster virus (VZV) specific immune response was studied using interferon (IFN)-γ enzyme-linked immunosorbent spot assay, proliferation assays and upregulation of T-cell activation markers in people with MS before (n=38) and after three months of fingolimod therapy (n=34), in untreated (n=33) and IFN-β-treated (n = 25) people with MS and in healthy controls (n=22). They used real-time PCR in 76 peripheral blood mononuclear cell samples and 146 saliva samples to analyse the viral replication.
They found that there was a marked reduction in CD3+ T cells with a relative decrease of naïve and central memory T cells and an increase of effector T cells in those treated with fingolimod. The absolute number of cells proliferating upon VZV stimulation was reduced in the blood of people treated with fingolimod. It was also noted that after fingolimod treatment, VZV-specific and EBV-specific IFN-γ-producing cells were reduced. 20% of people treated with fingolimod showed signs of VZV or EBV reactivation in saliva compared to three of the 111 controls. None showed signs of reactivation in the peripheral blood cells.
In conclusion, the people with MS treated with fingolimod demonstrated a slightly decreased antiviral T-cell response, which was accompanied by a subclinical reactivation of VZV or EBV in the saliva of some people treated with fingolimod.
Authors: Ricklin ME, Lorscheider J
Source: Neurology. 2013 May 22. [Epub ahead of print]
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