Figure 3. Treg cells from SAMP-F are dysfunctional in vivo and in vitro.

6-wk-old SCID mice were reconstituted with FACS-sorted MLN CD45RB^hi CD4⁺ T cells from SAMP-M alone (● RB^hi) or co-transferred with MLN CD45RB^low CD4⁺ T cells from either SAMP-M (■ RB^low-M) or SAMP-F (□ RB^low-F); vehicle, mock-transferred SCIDs served as controls (○ Ctrl). (A) Changes in body weight are shown in weeks post-transfer and (B) histologic evaluation of colitis is shown at 8 wks post-transfer. Percent change in body weight and composite inflammatory scores are represented as mean ± SEM (*p≤0.05, n=16/group). (C) Mean percentage of CD25⁺/Foxp3⁺ cells within the RB^low T cell population of SAMP-M and –F is expressed ± SEM. (D) Representative photomicrographs of colon from indicated mice (scale bar=100 µm; original magnification 20× + 1.25NA). (E) In vitro Treg suppression activity. CD4⁺CD25⁻ Tconv and CD4⁺CD25⁺ Treg cells were isolated from SAMP-M or SAMP-F mice. Tconv were cultured alone or with a 1:1 ratio of Treg for 3 days in the presence of αCD3/αCD28. Percent suppression is expressed as the percentage of Tconv proliferation that was suppressed by co-culture with Treg cells. Each dot represents one experiment (3 pooled mice per experiment) ± SEM.