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