HLA-DRB1 and-DQB1 alleles and gene polymorphisms of selected cytokines in systemic lupus erythematosus

The objective of this study was to evaluate the genetic profiles of selected cytokines (transforming growth factor beta 1, tumor necrosis factor alpha, interleukin-6, interferon gamma, and interleukin-10) in systemic lupus erythematosus and the contributions of human leukocyte antigen (HLA)-DRB1 and -DQB1 alleles to susceptibility for this disease. The study was carried out in 24 SLE patients and 36 healthy controls (from Upper Silesia) using polymerase chain reaction methods. All persons were of Caucasoid origin. Standard association analysis was used to compare the HLA alleles and frequency of cytokine gene polymorphisms between these groups. Only the frequency of HLA-DRB1*07 allele was higher in SLE patients than controls (odds ratio 2.92, 95% confidence interval 1.16-7.33), but the difference did not reach statistical significance when Bonferroni's adjustment procedure was performed. No other significant associations were noted between class II alleles (DR1-DR6, DR8-DR10, DQ1-DQ4) and SLE. The frequency of the interleukin-6 GG and GC genotypes was significantly higher in SLE patients than in controls, and a significantly higher percentage of the G vs C alleles between patients and controls was revealed (odds ratio 2.53, 95% confidence interval 1.37-4.65, chi-squared test 8.16, P < 0.05). The most significant association of increased frequency of the G allele with SLE was more commonly noted in HLA-DRB1*07-positive patients (odds ratio 10.29, 95% confidence interval 5.34-19.83, P < 0.001). These data indicate that this combination could contribute toward determining the susceptibility to SLE, but its possible significance will require confirmation by further studies.