Figure 6.

Effects of C3a on the T-cell stimulatory capacity of monocyte-derived dendritic cells (MoDC). MoDC (1 × 10⁴ cells/well) were either not stimulated or stimulated with C3a with or without interferon (IFN)-γ+ IFN-α to up-regulate the C3a receptor (C3aR). After 48 hr, MoDC were washed and autologous T cells (1 × 10⁵ cells/well) and tetanus toxoid (TT; 10 µg/ml) were added. After 5 days of co-culture, cell proliferation was determined by the incorporation of radioactive thymidine. MoDC prestimulated with tumour necrosis factor-α (TNF-α) + prostaglandin E₂ (PGE₂) (a known strong maturation stimulus) served as positive control, co-cultures of MoDC and T cells without TT, T cells and MoDC alone and T cells plus TT served as negative controls. The mean value ± standard error of the mean (SEM) from six independent experiments is shown. Prestimulation of MoDC with C3a did not alter their ability to induce T-cell proliferation with or without up-regulation of the C3aR. Maturation of MoDC with TNF-α+ PGE₂ resulted in an increase of the T-cell stimulatory capacity of MoDC as compared to the medium control.