Study of the natural course and specific immunity after herpes zoster in patients with rheumatoid arthritis receiving biologic DMARDs.

Herpes zoster is a common infection especially in elderly persons. It is caused by reactivation of varicella zoster virus (VZV) that has remained dormant within dorsal root ganglia after primary infection. Besides patients with immunodeficiency and malignancies, zoster incidence is also higher in patients with rheumatic diseases compared to the general population. Especially in the group of rheumatoid arthritis (RA) patients being treated with biologics, the risk seems to be steady among regimens with different modes of action (1.6-2.4/100 patients-years). RA patients receiving tumor necrosis factor (TNF) inhibitors are at increased risk during the first year of treatment. The aim of the current research protocol is to evaluate the natural course of herpes zoster and the effect of biologic and conventional synthetic disease modifying anti-rheumatic drugs (DMARDs) on the VZV-specific cell mediated immunity in RA patients after herpes zoster infection. We will - prospectively - include RA patients who develop herpes zoster, while being treated with biologics (anti-TNF, tocilizumab, rituximab, abatacept) and a control group comprised of patients with herpes zoster [RA patients under non-biologic therapies (corticosteroids/csDMARDs) and age- and sex-matched healthy controls). Titers of IgG specific antibodies against VZV glycoprotein gp1 and the percentage and absolute number of VZV-specific activated CD4+ T cells (CD4+CD69+IFN-γ+) at the time of rash onset and during follow-up will be measured by ELISA and flow cytometry respectively. This study will contribute to the better understanding of various aspects of immune response to VZV in the modern treatment era with biologic DMARDs.