Abstract: Objective To study the expression of interferon regulatory factor 1（IRF-1） in patients with systemic lupus erythematosus （SLE） and the influence of prolactin （PRL） upon it. Methods The level of serum PRL in quiescent condition was examined by electrochemiluminescence-meter in 30 patients with SLE and 20 healthy controls. Peripheral blood mononuclear cells（PBMC） were separated from all the subjects by gradient centrifugation density, and cultured with or without the presence of recombinant human PRL （rhPRL） for 24 hours. The expression of IRF-1 gene in cultured PBMC was detected by reverse transcriptase-PCR （RT-PCR） with gel image scanning. Results The relative value of IRF-1 gene expression was significantly higher in SLE patients than in normal controls （0.89 ± 0.21 vs 0.78 ± 0.18, P ＝ 0.026）, and in SLE patients with high PRL than in those with normal PRL （1.06 ± 0.26 vs 0.82 ± 0.21, P ＝ 0.005）. However, there was no significant difference between SLE patients with normal PRL and healthy controls in regard to the expression of IRF-1 gene（P ＝ 0.514）. The stimulation with rhRPL significantly elevated the relative expression of IRF-1 gene in SLE patients with normal PRL （0.99 ± 0.22 vs 0.82 ± 0.21, P ＝ 0.036）, but had no obvious effect on that in the normal controls. Conclusion The study reveals a high expression of IRF-1 gene in SLE patients, which may be related to the high level of PRL.

Key words: lupus erythematosus, interferon regulatory factor 1, prolactin