A seroepidemiological study of cytomegalovirus and Epstein-Barr virus in rheumatoid arthritis and sicca syndrome.

Antibodies to cytomegalovirus (CMV) and Epstein-Barr virus capsid antigen (EBVCA) were examined in 41 patients with rheumatoid arthritis (RA), 26 patients with primary sicca syndrome, and 26 healthy subjects of similar age and sex. IgG antibody titres to EBVCA and CMV were similar in all three groups, apart from a trivial increase of antibodies to EBVCA in RA. False positive IgM anti-CMV antibodies detected in serum from one patient with sicca syndrome and 20 patients with RA were shown to be due to rheumatoid factors. These data did not support recent suggestions that patients with these diseases showed exaggerated immunological responses to either virus and emphasised the need to incorporate adequate laboratory and disease controls when seroepidemiological studies are performed on sera containing rheumatoid factors and autoantibodies.