Profiling the expression of interleukin (IL)-28 and IL-28 receptor α in systemic lupus erythematosus patients.

BACKGROUND: Interleukin (IL)-28 is an interferon-λ-family member involved in immunity against viral infection and tumour. We here determined the expression profiles of IL-28 and IL-28 receptor α (IL-28RA) in patients with systemic lupus erythematosus (SLE) to evaluate the possibility that IL-28 is linked to the pathogenesis of SLE. MATERIALS AND METHODS: The serum IL-28 protein levels were determined by ELISA, and the IL-28 and IL-28RA transcript levels in peripheral blood mononuclear cells (PBMCs) and peripheral blood T cells were determined by RT-PCR. The levels in patients with SLE with the active disease activity were statistically compared with those in normal controls. RESULTS: IL-28 protein in sera and IL-28 transcripts in PBMCs and unactivated T cells were detectable only in some individuals, and IL-28 transcripts in T cells were induced by cell activation with anti-CD2, anti-CD3 and anti-CD28 antibodies. However, compared with normal controls, patients with SLE more frequently had detectable IL-28 protein in serum and had the higher IL-28 transcript levels in activated CD4(+) T cells, but not activated CD8(+) T cells. Two IL-28RA transcripts isoforms were detected in PBMCs and T cells, and their levels in patients with SLE were comparable with those in normal controls. CONCLUSIONS: The expression of IL-28, a T-cell autocrine factor, is dysregulated in patients with SLE, supporting the possibility that IL-28 may contribute to some of the SLE pathogenesis.