Association of rheumatoid factors in renal transplant recipients with cytomegalovirus infection and not with rejection

Because rheumatoid factors (RF) were detected in the circulation of the majority of early renal transplant recipients and could be eluted from rejected transplants, RF were hypothesized to be related to antibody responses to the histoincompatible graft, The possibility that RF production might have been related to infection and not rejection has not been considered previously. Therefore, we investigated serial serum samples from 147 adult renal transplant recipients for RF with latex agglutination and radioimmune assays. RF were detected in the sera of 32 patients, 30 of whom had coincident active cytomegalovirus (CMV) infections. Another 45 patients with active CMV infections did not have detectable circulating RF. In contrast, of 74 patients who experienced a total of 103 treated reversible or irreversible rejection episodes in the absence of evidence of active CMV infections, only 2 patients produced RF during their rejection episodes. Nino of the patients who did not produce RF during a rejection episode subsequently produced RF during a later CMV infection. These data indicate that RF production in renal transplant recipients is associated with CMV infection and not rejection. Moreover, EF production was found to be more frequently associated with primary and severe CMV infections than with secondary or milder CMV infections. RF production was not more frequent in patients who were HLA-DR-4-positive., older, or female, characteristics that have been associated with RF production in other populations. All of the sera, with detectable RF contained IgM antibodies that were directed to the Fc portion of human IgG, and about half contained additional IgM antibodies directed to Fab. Thus CMV infections may be the stimuli for the IgM anti-Fab antibodies that have been reported in pretransplant serum samples. Eleven patients produced IgG or IgA RF in addition to IgM RF during CMV infections.