CD14 cells inhibit the proliferative response of autologous preG-PBMC or preG-CD4 cells. Cultures were established with 5.0 × 10⁴ preG-PBMC (A) or 2.5 × 10⁴ preG-CD4 responders (B) and 1.0 × 10⁵ irradiated (30 Gy) allogeneic PBMC stimulators in the absence or presence of responder-derived preG- (solid lines) or G-(dashed lines) CD14 cells at the indicated numbers. Values for ³H-thymidine incorporation represent the mean cpm ± SEM from quintuplicate cultures with values from autologous background controls subtracted. Results from one of nine representative experiments are shown (three experiments for side-by-side comparison of preG- and G-CD14 cells).