Background: A biallelic polymorphism (--174 G/C) within the interleukin-6 (IL-6) promoter reportedly has functional importance through the modulation of IL-6 expression in vitro and in vivo.
Methods: We performed a population-based case-control study to analyse the association of the --174 G/C polymorphism with disease susceptibility and clinical manifestations in 211 German patients with systemic lupus erythematosus (SLE).
Results: There were no significant differences in allelic and genotypic frequencies between patients and healthy controls. Comparing patients with various disease manifestations, we found an association of the --174 G allele with discoid skin lesions (Pc=0.034) and anti-histone antibodies (Pc=0.009).
Conclusions: The IL-6 promoter polymorphism --174 G/C does not contribute significantly to disease susceptibility, but predisposes to distinct clinical and immunological features. A genetically determined high IL-6 response may have a pathogenic role under these conditions.