Relationship Between Polymorphisms of Interleukin-1 Receptor Antagonist (IL-1Ra) Genes and Susceptibility to Systemic Lupus Erythematosus in Iranian Population.

OBJECTIVES: Interleukin (IL)-1 has a major role in cell destruction and inflammation. IL-1 receptor antagonist (IL-1RN or IL-1Ra) is a natural anti-inflammatory molecule that blocks IL-1. We intended to determine whether IL-1RN or IL-1Ra variable number tandem repeat (VNTR) polymorphism is associated with susceptibility to systemic lupus erythematosus (SLE) in a series of patients in the Northeastern part of Iran. METHODS: Genomic DNA was extracted from the whole blood of 104 SLE patients and 209 subjects without SLE as a control group. The control group was matched for age and gender with SLE patients. Then, genomic DNA was genotyped by polymerase chain reaction (PCR) method for a length polymorphism in intron 2 of the IL-1RN gene. RESULTS: Of five alleles, only allele 4 of IL-1RN had a higher frequency in healthy subjects (2.4%) compared to SLE patients (0), with a statistically significant difference (P= 0.03). Eleven kinds of polymorphisms of IL-1RN were found including 1/1, 1/2, 2/2, 3/3, 1/3, 3/5, 2/3, 2/5, 1/5, 4/4 and 1/4 in both groups. In genotype frequency, there was no statistically significant difference regarding gene polymorphism kinds between the two groups (P= 0.29). CONCLUSION: Alleles 4 of IL-1RN may have a protective role against SLE susceptibility. However, SLE was not associated with any of the 11 kinds of genotype IL1-RN gene polymorphisms studied here.

Association of HLA-DQB1 allelic sequence variation with susceptibility to systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is an autoimmune disease in which polymorphisms within the human leukocyte antigen (HLA) region have been associated to its etiology. We conducted this study to compare the HLA-DQB1 allelic sequence variation among SLE patients and controls in the northeast of Iran. Genomic DNA of 40 SLE patients and 83 healthy controls were amplified by Polymerase Chain Reaction with Sequence-Specific Primers technique (PCR-SSP). Seven serological subclasses of the HLA DQB1 were detected. Allele distribution comparison showed in the SLE group a significant increase of HLA DQ6 (*0601-*0609) (p=0.006); whereas alleles HLA DQ7 (*0301-*0304) were significantly decreased (p=0.005). Combination of DQ5 (*0501-*0504)-DQ6 (*0601-*0609) was increased in patients. These results suggest that DQ6 is the dominant HLA DQB1 allele probably associated with genetic susceptibility to SLE in the northeast of Iran. The association supports the importance of ethnic background and indicates the importance of various genes that has been observed in different SLE populations.