rs1800871 — IL10 -819 C>T

IL-10 Production — The Third Promoter Signal

Interleukin-10 (IL-10) is the body's master anti-inflammatory cytokine, acting as a potent brake on immune responses. The IL10 gene on chromosome 1¹¹ chromosome 1
Located at 1q31-32, position 206,773,289 (GRCh38) encodes this regulatory cytokine. The -819 C>T polymorphism (rs1800871) sits in the promoter region approximately 819 base pairs upstream of the transcription start site, forming part of a three-SNP haplotype system that is the primary genetic determinant of how much IL-10 a person's immune cells produce.

This is the third of three core IL-10 promoter variants in GeneOps — rs1800896 (-1082 A>G) and rs1800872 (-592 C>A) are the other two. Together they define the complete IL-10 production haplotype.

The Mechanism

The IL10 promoter region contains three highly polymorphic positions that travel together on chromosomes in strong linkage disequilibrium²² strong linkage disequilibrium
These three SNPs are so tightly linked that knowing two alleles usually predicts the third, forming three predominant haplotypes:

• GCC haplotype (positions -1082G / -819C / -592C): Associated with high IL-10 production
• ATA haplotype (-1082A / -819T / -592A): Associated with low IL-10 production, 2–4 fold reduction in promoter activity
• ACC haplotype (-1082A / -819C / -592C): Intermediate IL-10 production

The -819 position (rs1800871) falls within a transcription factor binding region³³ transcription factor binding region
The promoter region controls how actively the IL10 gene is copied into mRNA. The C allele (coding strand) corresponds to the G allele on the genomic plus strand (since IL10 is transcribed from the minus strand). Luciferase reporter assays show that the ACC construct — which contains the C allele at -819 — shows weaker promoter activation compared to GCC, while the ATA construct shows selective repression in trophoblasts and constitutive activation in monocytes, highlighting cell-type-specific and stimulus-specific regulation⁴⁴ cell-type-specific and stimulus-specific regulation
The same allele can have different effects depending on immune context rather than a simple high/low binary.

IL-10 operates in a paradoxical space: higher production generally dampens acute inflammation⁵⁵ higher production generally dampens acute inflammation
IL-10 suppresses TNF-α, IL-6, IL-1β synthesis in monocytes and macrophages, but chronically elevated IL-10 can promote B-cell survival, autoantibody class switching, and impaired anti-tumor immunity. This explains why the C allele (high producer, GG genotype on plus strand) is associated with both increased autoimmune risk and increased gastric cancer risk.

The Evidence

Systemic Lupus Erythematosus: A case-control study in 116 Iranian SLE patients vs. 131 healthy controls⁶⁶ 116 Iranian SLE patients vs. 131 healthy controls found the CC genotype at -819 (GG on plus strand) was associated with significantly increased SLE susceptibility (OR=3.38, 95% CI 1.26–9.07). The C allele was identified as the risk allele (OR=1.86, 95% CI 1.15–3.01). High IL-10's role in promoting B-cell activation and autoantibody production likely explains this finding.

Gastric Cancer: The C allele increases gastric cancer risk. A Chinese case-control study⁷⁷ Chinese case-control study
279 gastric cancer patients vs. 296 controls found that the C allele was associated with elevated gastric cancer risk (additive model OR=1.33, recessive model OR=1.46). A separate Chinese study⁸⁸ Chinese study
208 gastric cancer patients, 116 atrophic gastritis patients, 232 controls found the CC genotype significantly increased gastric cancer risk, while the TT genotype (AA on plus strand, low producer) was protective. Two meta-analyses confirm this pattern⁹⁹ Two meta-analyses confirm this pattern: the TT genotype is protective specifically in Asians (OR=0.86, 95% CI 0.76–0.98), while a 2024 systematic review of 15 studies encompassing 7,779 participants¹⁰¹⁰ 2024 systematic review of 15 studies encompassing 7,779 participants confirmed the allelic model association. High IL-10 from the CC/GCC haplotype may suppress anti-tumor immunity, allowing pre-malignant cells to escape immune surveillance.

IgA Nephropathy: In a Chinese Han population study¹¹¹¹ Chinese Han population study
351 IgAN patients vs. 310 controls, rs1800871 was significantly associated with increased IgA nephropathy risk across all genetic models, suggesting that the -819 C allele contributes to the autoimmune dysregulation underlying glomerulonephritis.

Preeclampsia: The low-producer ATA haplotype (containing the -819 T allele, A on plus strand) showed paradoxically increased risk for preeclampsia in a Tunisian study of 345 preeclampsia cases vs. 300 controls¹²¹² Tunisian study of 345 preeclampsia cases vs. 300 controls (OR=1.65, 95% CI 1.13–2.43 after multivariate adjustment). This reflects the importance of adequate IL-10 for immune tolerance during pregnancy — insufficient IL-10 may allow maternal inflammatory responses to target the placenta.

Cancer Haplotype Analysis: A meta-analysis of 12 case-control studies¹³¹³ meta-analysis of 12 case-control studies
2,090 cancer cases vs. 4,224 controls found the GCC haplotype (high producer, containing -819 C allele) was associated with 47% higher cancer risk compared to ATA (OR=1.47, 95% CI 1.25–1.72) across both Caucasian and non-Caucasian populations.

Practical Implications

Your genotype at rs1800871 determines which of the three IL-10 promoter haplotypes you carry. The GG genotype (plus strand) — corresponding to the C allele on the coding strand and membership in the high-producer GCC haplotype — confers increased risk for autoimmune conditions (SLE, IgA nephropathy) and paradoxically also for gastric cancer, through IL-10's immune-suppressive effects on tumor surveillance.

The AA genotype (low producer, ATA haplotype) carries a different risk profile: reduced capacity to dampen inflammation increases vulnerability in pregnancy (preeclampsia) while providing modest protection against gastric cancer in East Asian populations.

For high producers (GG genotype), the most relevant interventions are monitoring for early signs of autoimmune disease and avoiding factors that further dysregulate immune balance. For low producers (AA genotype), particularly during pregnancy or with active inflammatory disease, strategies to support IL-10 pathways through omega-3 fatty acids and curcumin are evidence-based.

Interactions

The -819 C>T variant (rs1800871) is part of the three-SNP IL-10 promoter haplotype system with rs1800896 (-1082 A>G)¹⁴¹⁴ rs1800896 (-1082 A>G)
The primary IL-10 promoter variant in the GeneOps database and rs1800872 (-592 C>A)¹⁵¹⁵ rs1800872 (-592 C>A)
The third IL-10 promoter variant. The three sites are in strong linkage disequilibrium — knowing all three positions enables complete haplotype classification:

• If GG at rs1800871, GG at rs1800896, and GG at rs1800872: full GCC haplotype homozygote (highest IL-10 producer) — OR=2.77 for severe COVID-19 in the Brazilian cohort through excessive immunosuppression
• If AA at rs1800871, TT at rs1800896, and TT at rs1800872: full ATA haplotype homozygote (lowest IL-10 producer) — highest inflammatory susceptibility but lowest risk of IL-10-mediated immune suppression

There is a proposed compound action combining genotypes across all three IL-10 promoter SNPs to classify full haplotype status, which provides stronger predictive power than any single variant alone.