Figure 5.

IL-6 and TNF-α synergized to impair the suppressive function of Tregs. (A) CD4⁺CD25⁻ T cells were stimulated with soluble anti-CD3 with or without the co-culture of CD4⁺CD25⁺ Tregs. Recombinant IL-6, TNF-α, or both were added to the cultures. Results are presented as counts per minute or percentage suppression of T effector proliferation mediated by Tregs. (B) C57BL/6 CD4⁺CD25⁻ T cells were stimulated with BALB/c APCs with or without co-culture of CD4⁺CD25⁺ Tregs. Recombinant IL-6, TNF-α, or both were added to the cultures. Results are presented as counts per minute or percentage suppression of T effector proliferation mediated by Tregs. (C) CD4⁺CD25⁻ T cells were stimulated with soluble anti-CD3 and cultured alone or co-cultured with increasing numbers of CD4⁺CD25⁺ Tregs from C57BL/6 WT and IL-6^−/−TNF-α^−/− mice, and proliferation was measured. IL-6^−/−TNF-α^−/− Tregs exhibited a similar ability to suppress T effector proliferation compared with WT Tregs.