[Effect of monocytes activated with lipopolysaccharide on human Th17 cell differentiation]

To investigate whether monocytes activated with lipopolysaccharide(LPS) have an effect on Th17 cell differentiation in humans, CD4(+) T cell and CD14(+) monocytes activated with LPS were treated in the absence or presence of anti-CD3 mAb with various concentrations at different time points.

Purification of CD4(+) T cell and CD14(+) monocytes were performed by magnetic cell sorting and cultured together. Cultures were stimulated with LPS alone or anti-CD3 mAb alone or LPS plus anti-CD3 mAb for 3 days. In the anti-CD3 mAb stimulation cells were added different concentrations of LPS. Cells were activated under LPS/anti-CD3 costimulation for 3, 6, or 10 days. The percentage of IL-17(+) T cells and INF-γ(+) T was determined by flow cytometry.

LPS or anti-CD3 mAb alone induced only very low levels of IL-17(+) T cells, (1.30 ± 0.19)%, (1.10 ± 0.21)%, respectively. The percentage was substantially higher in the LPS and anti-CD3 mAb costimulationa as much as(2.01 ± 0.46)%. In the presence of 0.1 μg/mL, 1 μg/mL, 10 μg/mL LPS, the proportion of Th17 reached to (1.92 ± 0.21)%, (1.30 ± 0.37)%, (1.01 ± 0.25)%. Low-concentration LPS (0.1 μg/mL) stimulation favored Th17 differentiation. The highest proportion of IL-17(+) T cells was found at day 3(2.13 ± 0.32)%, with levels declining at day 6 and day 10, while, Th1 at day 6(17.45 ± 3.04)%, declining at day 10.

Low-concentration LPS stimulation plus anti-CD3 mAb in short term support optimal Th17 generation. Nevertheless, this model closely mimics the environment of rheumatoid arthritis in vivo and proposes an effective model for the generation of human Th17 cells.