RA patients had significantly higher titers of anti-EBV-CA IgM and anti-EBV-EA(D) IgG antibodies than controls (p = 0.003 and p = 0.023, respectively), whilst titers of anti-EBV-EBNA1-IgG were significantly higher in controls than in RA patients (p = 0.001). This evidence concerns the gene CD40LG and rheumatoid arthritis.