Mosaics of gene variations in the interleukin-10 gene promoter affect interleukin-10 production depending on the stimulation used

Interleukin-10 (IL-10), a cytokine involved in many aspects of the immune response shows interindividual variations in their expression. However, genetic variations of the 5'-flanking region of the IL-10 gene (PIL-10) are poorly characterised with respect to different stimuli. New extended haplo- and genotypes are identified present at differing frequencies in three geographically separated populations. Their influence on IL-10 expression have been assessed in vitro after stimulation of leukocytes with lipopolysaccharide (LPS), dibutyryl-cAMP or following immortalisation with Epstein-Barr virus (lymphoblastoid cell line (LCL)). Interindividual differences of IL-10 production were found to be related to single-nucleotide polymorphisms (SNP) haplotype -6752/-6208 in LCLs (P < 0.02), and for haplotypes comprising SNPs -6752/-6208/-3538 after LPS stimulation (P < 0.03). Carriers of the IL10.G microsatellite with 22, 24 or 26 dinucleotide repeats linked with the -1087G SNP, exhibited the highest levels of IL-10 expression. Contrasting IL-10 secretion patterns were found for IL10.R microsatellite alleles characterised by 15 dinucleotide repeats: after LPS stimulation this allele was associated with high IL-10 production (P < 0.007), but with low IL-10 levels in LCLs (P < 0.038). Thus, the effects of mosaics of genetic elements in the PIL-10 on the capacity of leukocytes to produce IL-10 depend on the agent inducing IL-10 expression.