Regulation of T-cell alloproliferation by post-G^MLRCD4⁺ T cells is antigen nonspecific.

Freshly isolated pre-G and post-G CD4⁺ T cells from the same donor were separately primed with allogeneic TCD PBMCs from a different healthy volunteer (donor A or donor B). After 7 days, secondary cocultures were set up by placing donor A–specific or donor B–specific pre-G ^MLRCD4⁺ T cells in the lower chamber of a Transwell separated from donor A–specific post-G ^MLRCD4⁺ T cells by a semipermeable membrane. Both compartments of the secondary Transwell culture received allogeneic TCD PBMCs (donor A or donor B, as indicated in the figure) 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 coculture by the addition of BrdUrd for the final 24 hours. (A) Median values and ranges recorded in 6 independent experiments are shown. *P < .05 compared with pre-G^MLRCD4⁺ T cells. (B) Regulation of T-cell proliferation to recall antigens by post-G^MLRCD4⁺ T cells. Freshly isolated pre-G or post-G ^MLRCD4⁺ T cells were activated with TCD PBMCs from an allogeneic donor and were cocultured with pre-G CD4⁺ T cells stimulated with PPD-pulsed autologous DCs (see “Patients, materials, and methods”). Proliferation of pre-G 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. *P < .05 compared with pre-G CD4⁺ T cells.