Figure 6.

Suppression of Treg cells under inflammatory conditions. (A) Representative histograms indicating the CFSE dilution from a sample cultured without rhIL-6 and a sample cultured with 25 ng/ml rhIL-6. The proliferation curve of Teff cells cultured alone (red) was overlaid with the curve for Teff cells co-cultured with Treg cells (blue). (B-D) The sorted Teff cells from healthy blood donors (n=8) were labelled with CFSE and co-cultured with sorted Treg cells (Teff cells/Treg cells, 2:1) in the presence of anti-CD3/CD28 beads (Teff cells/beads, 1:1), without or with 25 ng/ml rhIL-6. After co-culture for 5 days, Teff-cell proliferation was assessed by flow cytometry, and (B) the proportion of responding T-cells, (C) doubling time of a single T-cell and (D) proliferative capacity for the Teff cells were calculated. Paired Student's t-test was used to compare differences between groups without and with rhIL-6. Values are expressed as the mean ± standard error of the mean (n=8). *P<0.05 and **P<0.01 compared the doubling time of a single T-cell and proliferative capacity of Teff cells cultured for 5 days without vs. with Treg cells. Treg cells, T-regulatory cells; Teff cells, T effector cells; CFSE, 5,6-carboxyfluorescein succinimidyl ester; rhIL, recombinant human interleukin.