Thorax 58:154-156 doi:10.1136/thorax.58.2.154
  • Short papers

Association of IL-10 polymorphism with severity of illness in community acquired pneumonia

  1. P M Gallagher1,
  2. G Lowe1,
  3. T Fitzgerald2,
  4. A Bella1,
  5. C M Greene1,
  6. N G McElvaney1,
  7. S J O’Neill1
  1. 1Division of Respiratory Research, Department of Medicine, RCSI Education and Research Centre, Royal College of Surgeons in Ireland, Beaumont Hospital, Dublin, Ireland
  2. 2Department of Epidemiology, Royal College of Surgeons in Ireland, Dublin, Ireland
  1. Correspondence to:
    Dr S J O’Neill, Division of Respiratory Research, Department of Medicine, Royal College of Surgeons in Ireland Education and Research Centre, Beaumont Hospital, Dublin 9, Ireland; cmgreene{at}
  • Accepted 2 October 2002
  • Revised 11 September 2002


Background: The influence of genetic polymorphisms of interleukin (IL)-10, tumour necrosis factor (TNF)-α, and IL-6 gene promoters on severity of systemic inflammatory response syndrome (SIRS) associated with community acquired pneumonia (CAP) was studied.

Methods: Using PCR-RFLP analysis we analysed a −1082G/A single nucleotide polymorphism (SNP) of the anti-inflammatory IL-10 gene, a −308G/A SNP of the pro-inflammatory TNF-α gene and a −174G/C SNP of the IL-6 gene. Illness severity was stratified according to SIRS score, calculated by presence of up to four physiological indices: temperature, white blood cell count, heart rate and respiratory rate (non-SIRS, SIRS 2, SIRS 3, and SIRS 4).

Results: A statistically significant stepwise increase in frequency of the IL-10 G allele, associated with higher expression of the gene, was observed in patients with increasing severity of illness from non-SIRS (n=19) to SIRS 2 (n=17), SIRS 3 (n=33) and SIRS 4 (n=24). This was primarily due to a higher frequency of the GG genotype with increasing severity from non-SIRS through to SIRS 4. IL-10 G allele frequency was also increased in patients who died as a result of CAP (n=11) compared with CAP survivors (n=82) (p=0.01). No association was seen between the TNF-α −308G/A and IL-6 −174G/C SNPs and disease. Additionally, no interaction between all three SNP genotypes and disease severity was observed.

Conclusions: A polymorphism affecting IL-10 expression may influence the severity of illness in patients with CAP.