IFN-λ1 increased the chemokines response to LPS. Whole PBMC were incubated in the presence of IFN-λ1 for 30 minutes before the addition of LPS at the doses indicated. Cells were then incubated for 72 h before being assessed for levels of IP-10 (a), MIG (b) and IL-8 (c) in culture supernatants using ELISA. only 50 ng/ml IFN-λ1 showed an assistant effect on the chemokine IP-10 secretion (P = 0.016) (a). Different concentrations of IFN-λ1 all played a synergistic role in the effect of LPS (P = 0.047, 0.013, 0.038) (b). Both 10 ng/ml and 100 ng/ml IFN-λ1 displayed this synergistic effect on the secretion of chemokine IL-8 (P < 0.001, P = 0.002) (c). *, P < 0.05, **, P < 0.01. means ± s.d. are shown. ELISA, enzyme-linked immunosorbent assay; IFNλ1, interferon λ1; IL-8, interleukin-8; IP-10, IFN-inducible protein-10; LPS, lipopolysaccharide; MIG, monokine induced by interferon-γ; NC, normal control; PBMC, peripheral blood mononuclear cells; SLE, systemic lupus erythematosus.