Genetically determined interferon-γ production influences the histological phenotype of lupus nephritis

Objective. To clarify whether the interferon-gamma (IFN-gamma) gene (IFNG) is associated with the histological phenotype of lupus nephritis. Method. We analysed microsatellite polymorphisms located within the first intron of the IFNG gene to determine the genotypes of patients with lupus nephritis WHO class IV (n=24), patients with WHO class V (n=12) and healthy controls (n=61). We used flow cytometric detection of intracellular cytokines to identify CD4(+) T cells producing IFN-gamma. Production of IFN-gamma, by peripheral blood mononuclear cells after stimulation with phytohaemagglutinin was evaluated with an enzyme-linked immunosorbent assay. Result. The frequency of the IFNG allele 114 was significantly greater in WHO class V patients than in WHO class IV patients. Furthermore, the IFNG 114 +/+ genotype Was more frequent in WHO class V than in WHO class IV patients. The level of IFN-gamma and the percentage of IFN-gamma-producing CD4(+) T cells were lower in individuals with genotype 114 +/+ than in individuals with genotype 114-/-. Conclusion. The IFN-gamma gene is associated with the histological phenotype in lupus nephritis.