Figure 3

Cross-linking of CTLA4 inhibits DC maturation (A), the mixed lymphocyte response (B), and antigen presentation (C). *: P < 0.05 anti-CTLA4 antibody vs control antibody. A representative of three experiments is shown. A: Relative mean fluorescence intensity (MFI; MFI_treated - MFI_iDC) of CD83 was measured. DCs were seeded in wells coated with anti-CTLA4 antibody or isotope control antibody at the indicated concentrations, and mature DCs were used as the positive control. B: Mature DCs after challenge in plates coated with anti-CTLA4 or control antibody were used as the stimulators and allogeneic PBMC-derived T lymphocytes as the responders. DCs and T cells were mixed in different ratios with a constant number of T cells (2 × 10⁵ cells/well). T-cell proliferation was measured in triplicate by the incorporation of [³H]-thymidine and is expressed as cpm. C: Effect of CTLA4 cross-linking on the presentation of PPD to specific T-cell lines. After PPD pulsing, DCs were further cultured with maturation-inducing stimuli in plates coated with anti-CTLA4 antibody or control antibody at the indicated concentrations. The cells were then washed extensively and mixed with PPD-specific autologous T-cell lines. Proliferation was assessed as [³H]-thymidine uptake.