Interleukin-10 promoter microsatellite polymorphisms influence the immune response to heparin and the risk of heparin-induced thrombocytopenia

Abstract 

Introduction

Heparin-induced thrombocytopenia (HIT) results from an atypical immune response with synthesis of IgG antibodies (Abs) to platelet factor 4/heparin complexes (PF4/H), and probably involves both B and T cells. We investigated whether 3 single nucleotide polymorphisms (SNPs), rs1800896 (−1082G/A), rs1800871 (−819C/T) and rs1800872 (−592C/A) and the polymorphic CA repeat microsatellites IL10R [5325CA(11_15)] and IL10G [8134CA(14_29)] are associated with the synthesis of Abs to PF4/heparin and HIT.

Materials and methods

Eighty-two patients with definite HIT and two control groups were studied. The first control group (Ab^neg) consisted of 85 patients without Abs to PF4/heparin after cardiopulmonary bypass (CPB). The second control group (Ab^pos) consisted of 84 patients who had developed significant levels of PF4-specific antibodies after CPB, but without HIT.

Results

Allele frequencies of the 3 SNPs were similar in HIT patients and controls. Fourteen alleles in IL10G (G16 to G29) and 3 alleles in IL10R (R13 to R15) were defined. The short G20 allele of IL10G was more frequent in Ab^neg patients (8.2%) than in Ab^pos (2.9%) and HIT patients (3%). It thereby appeared to protect against developing Abs to PF4/heparin (OR 0.29; 95% CI [0.12-0.70], p=0.006). Combined haplotypes cH1/cH8 comprising the short G20+R13 alleles were less frequent in HIT (OR 0.33; 95% CI [0.11-0.97], p=0.036), and levels of Abs to PF4 in Ab^pos patients were lower in cH1/cH8 subjects (p=0.019).

Conclusion

These results suggest that IL10 promoter microsatellite polymorphisms might influence the immune response against PF4/heparin and the risk of HIT.

Keywords: heparin, thrombocytopenia, IL10, gene polymorphisms