Interleukin-1B (IL-1B-31 and IL-1B-511) and interleukin-1 receptor antagonist (IL-1Ra) gene polymorphisms in primary immune thrombocytopenia

BACKGROUND: Immune thrombocytopenia (ITP) is an immune-mediated disease caused by autoantibodies against platelets membrane glycoproteins GPIIb/IIIa and GPIb/IX. The etiology of ITP remains unclear. This study evaluated the association of polymorphisms in interleukin (IL)-1B-31, IL-1B-511, and IL-1Ra with ITP. METHODS: Genotyping of IL-1B-31, IL-1B-511, and IL-1Ra was performed in 118 ITP patients and 100 controls by polymerase chain reaction restriction fragment length polymorphism and detection of variable number tandem repeats. RESULTS: Genotype differences in IL-1B-31 and IL-1Ra were significantly associated with ITP. Patients showed a higher frequency of the IL-1B-31 variant allele (T) and a 1.52-fold greater risk of susceptibility to ITP (odds ratio [OR]=1.52, 95% confidence interval [CI]=1.04–2.22, P=0.034). The frequencies of both homozygous and heterozygous variant genotypes of IL-1B-31 were higher (OR=2.33, 95% CI=1.069–5.09, P=0.033 and OR=2.044, 95% CI=1.068–39, P=0.034) among patients and were significantly associated with ITP susceptibility. Both homozygous and heterozygous variant genotypes of IL-1Ra were also more frequent (OR=4.48, 95% CI=1.17–17.05, P=0.0230 and OR=1.80, 95% CI=1.03–3.14, P=0.0494) among patients and were associated with ITP risk. IL-1B-31 and IL-1Ra also showed significant association with severe ITP. However, IL-1B-511 was not associated with ITP. CONCLUSION: IL-1B-31 and IL-1Ra polymorphisms may significantly impact ITP risk, and they could be associated with disease severity, which may contribute to the pathogenesis of ITP.