The functional properties of Th17 cells can be affected under polarizing conditions induced by infection or immunization.25 Using the Th1/Th17-inducing antigens EbhA, IsaA and SdrE, we studied the plasticity of responding cells in terms of CD4+ T-cell proliferation and cytokine (IL-17/IFN-γ/IL-10) production, using in vitro polarization by modulatory pro- or anti-inflammatory cytokine combinations. Here, CD4 is linked to infection.