Mixed lymphocyte cultures using increasing numbers of preG-PBMCs (A) and G-PBMCs (B) cultured with 100 × 10³irradiated, allogeneic PBMC stimulators in the presence (solid line) or absence (dashed lines) of 10 μg/mL CTLA4Ig. Values for³H-thymidine incorporation represent the mean counts per minute (cpm) ± the standard error of the mean (SEM) from triplicate cultures. Results from one of three representative experiments are shown.