Resistance to human cytomegalovirus infection may be influenced by genetic polymorphisms of the tumour necrosis factor-alpha and interleukin-1 receptor antagonist genes.

To examine whether there are genetic differences between cytomegalovirus (CMV)-seronegative and CMV-seropositive adults, the polymorphisms of cytokine genes were analysed in a cohort of 400 adult blood donors. The genes and polymorphic sites studied were the tumour necrosis factor-alpha (TNF-alpha) gene (base exchange polymorphism at position -308; alleles TNF1 and TNF2) and the interleukin-1 receptor antagonist (IL-1RA) gene (variable numbers of 86-bp repeats in intron 2). In this material there were 85 (21%) seronegative persons. The frequencies of the TNF2 and the IL-IRA allele 2 (IL1RN*2) carriers were slightly increased in the seronegative compared with the seropositive samples (39% vs. 29%, and 55% vs. 47%, respectively). The presence of both of these alleles together was significantly (p < 0.05, chi2-test) more frequent in the seronegative population. These data suggest that the alleles of these cytokines, which are known to be associated with a strong inflammatory reaction, may have a protective role against CMV infection.