Exacerbation of chronic active Epstein–Barr virus infection in a patient with rheumatoid arthritis receiving humanised anti-interleukin-6 receptor monoclonal antibody

Abstract
We describe deterioration of chronic active Epstein–Barr virus (CAEBV) infection in a patient with rheumatoid arthritis who received a single infusion of humanised anti-IL6 receptor monoclonal antibody (tocilizumab). A 60-year-old woman with rheumatoid arthritis who had been treated with methotrexate developed lymphadenopathy in October 1999, which was ameliorated in 2 months by cessation of methotrexate. Re-institution of methotrexate in September 2000 led to recurrence of lymphadenopathy, which was diagnosed as necrotising lymphadenitis by histological examination, with high titres of anti-Epstein–Barr virus (EBV) antibodies (antiviral capsid antigens IgG 1:1280, anti-early antigens IgG 1:640) and EBV DNA in plasma (3100 copies/ml). The lymphadenopathy gradually disappeared after cessation of methotrexate at the expense of active arthritis. In July 2001, the patient was …