Interleukin-1 receptor antagonist (IL-1Ra) and also mononuclear cell-attractant chemokines CCL3, CCL4 and CCL5 have been implicated in the immunopathogenesis of primary Sjögren syndrome (pSS). Both the gene coding for receptor CCR5 binding the aforementioned CCL ligands and the gene for IL-1Ra are polymorphic. We have therefore in a case control study assessed the putative role of these "candidate" polymorphic genes in the inflammatory process in Sjögren syndrome.
DNA was obtained from 39 unrelated patients with primary Sjögren's syndrome and 76 unrelated healthy controls; all subjects were Caucasians of Slovak origin. CCR5 delta 32 and IL-1Ra VNTR polymorphisms were genotyped by PCR-SSP.
The frequencies of CCR5 delta 32 in patients with pSS were different from that in control subjects: there was an apparent decrease of the mutant allele in the patient group. CCR5 delta 32/CCR5 heterozygosity was associated with a reduced relative risk of pSS (OR 0.35, p = 0.043). There was no difference in the distribution of the alleles of the IL-1Ra VNTR polymorphism between the groups of pSS patients and control subjects.
In this population of patients with Sjögren's syndrome, the frequency of CCR5 delta 32/CCR5 genotype is significantly decreased. The data suggests that carrier status for the CCR5 delta 32 allele may contribute to protection from the development of primary Sjögren's syndrome. In contrast, IL-1Ra VNTR polymorphism does not confer susceptibility to primary Sjögren's syndrome in Slovak Caucasians.