Fig 8. S. aureus biofilm is able to promote expansion of CD4⁺CD25⁺Foxp3⁺ Tregs from CD4⁺ lymphocytes through modulation of MDSC function in vitro.

(a and b) The CD11b-positive MDSC fractions were individually isolated from BMCs that were untreated or treated with different amounts (0.2, 0.6 and 2.0 mg/ml) of biofilm. The isolated CD11b-positive MDSCs were subsequently cocultured with spleen T cells (activated by anti-CD3/CD28 beads) at a 1:1 ratio. After 24- or 48-hr coculture, the frequency of CD4⁺CD25⁺Foxp3⁺ T cells was analyzed by flow cytometry using a Treg Flow kit. (c and d) Bars indicate the percentages of CD4⁺CD25⁺Foxp3⁺ T cells out of CD4⁺ lymphocytes in coculture experiments as described above (N = 2).