Fig. 5.

SLAMF3 costimulation restores the IL-2 response in human naïve CD4⁺ T cells and promotes Treg differentiation. (A and B) Naïve CD4⁺ T cells from SLE and healthy controls were stimulated for 18 h, after which expression of CD25 (SLE, n = 9; controls, n = 9) (A) and pSTAT5 (SLE, n = 17; controls, n = 17) (B) was evaluated by flow cytometry. (C) Naïve CD4⁺ T-cell proliferation was expressed as the percentage of CFSE-low cells after 6 d of stimulation (SLE, n = 4–5; controls, n = 5–7) without exogenous cytokine (Left) or in the presence of recombinant IL-2 (50 IU/mL) (Right). (D) Naïve CD4⁺ T cells from SLE and controls were coactivated with anti-SLAMF3 mAb (solid line) or an isotype control (dashed line) and polarized under Treg conditions for 6 d. Their suppressive capacity was evaluated by measuring inhibition of Tconv proliferation (SLE, n = 3; controls, n = 3). Data are mean ± SEM.