Fig. 4.

Interferon (IFN)-γ-dendritic cells (DC) cause T cell hyporesponsiveness. Monocytes were treated with 500 U of IFN-γ (IFN-γ-DC) or cultured in the absence of IFN-γ (UT-DC) for 24 h in the presence of interleukin (IL)-4 and granulocyte–macrophage colony-stimulating factor (GM-CSF), then matured with tumour necrosis factor (TNF)-α and prostaglandin E₂ (PGE₂) for another 24 h. T cells (1 × 10⁵) were incubated with DC, at a DC to T cell ratio of 1:10, 1:100 and 1:1000 for 5 days. Proliferation was determined by [³H]-thymidine incorporation (counts per minute). Mean ± standard deviation of quintuplicate within experiment. *P < 0·0006. Representative of 10 independent experiments.