Association of tumour necrosis factor alpha and interleukin 6 levels with cytomegalovirus DNA detection and disease after renal transplantation

Cytokines such as tumour necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) are thought to be important in the pathogenesis of post-transplant cytomegalovirus (CMV) disease. CMV infection increases the production of TNF-α and IL-6. Conversely, TNF-α switches on the replication of CMV. To study the association of these two cytokines with CMV activity and disease, TNF-α and IL-6 levels were assayed in plasma samples taken serially from three groups of renal transplant recipients. Group A (n = 12) had CMV disease and syndrome; Group B (n = 11) had detectable CMV DNA in plasma or peripheral blood leucocytes without disease, i.e., presumed asymptomatic CMV infection, and Group C (n=11) had no detectable CMV DNA nor disease. The median peak TNF-α levels in patients with CMV disease (Group A) were significantly higher than that in Group B or Group C (P<0.02) whereas the median peak IL-6 levels in group C patients were significantly lower than that in group A (P<0.04) or group B (P<0.03). A TNF-α level of above 100 pg/ml was significantly associated with CMV disease and high plasma CMV load (> 10,000 copies/ml). IL-6 levels above 15 pg/ml were significantly associated with CMV DNA detection, but not with CMV disease or elevated CMV load. High levels of TNF-α or IL-6 were not associated with CMV donor/recipient serostatus, HHV-6 or HHV-7 DNA detection, immunosuppressive regimen or rejection episodes. The role of TNF-α in the pathogenesis of CMV disease deserves further investigation.