Regulation of T-cell alloproliferation by post-G^MLRCD4⁺ T cells is cell-contact independent and is affected in part by soluble IL-10 and TGF-β1.

(A) Freshly isolated post-G CD4⁺ T cells were immediately cocultured with pre-G CD4⁺ T cells from the same donor; both compartments of the Transwell system received allogeneic TCD PBMCs as stimulator cells and responder cells at a 1:3 ratio. Proliferation of indicator CD4⁺ T cells in the lower chamber of the Transwell was determined after 7 days of primary coculture by the addition of BrdUrd for the final 24 hours. Median and range recorded in 6 independent experiments are shown. *P < .05 compared with pre-G^MLRCD4⁺ T cells. (B) Primary cocultures were performed in the presence or absence of neutralizing antibodies directed against TGF-β1 (αTGF-β1; 20 ng/mL) or IL-10 (αIL-10; 10 μg/mL) or the combination of both mAbs. Control cultures contained an isotype-matched irrelevant mAb added at the same concentration as the αIL-10 and αTGF-β1 antibodies. Median values and ranges recorded in 6 independent experiments are shown. *P < .05 compared with pre-G^MLRCD4⁺ T cells.