Inhibition of T_reg function by DC1 dendritic cells results from a soluble factor.

<p>(<i>3A</i>) 1.25×10⁵ sorted, purified CD4+CD25+ T cells were co-cultured with 2.5×10⁵ CFSE-labeled unfractionated responder lymphocytes and 1×10⁵ immature dendritic cells (solid line) or DC1 dendritic cells for 5 days (dashed line). Data shown are gated on CD4-positive cells and are representative of at least 10 experiments. (<i>3B</i>) 1.25×10⁵ T_regs were co-cultured with 2.5×10⁵ CFSE-labeled responders and 1×10⁵ immature dendritic cells for 5 days (solid line). In addition, 1×10⁵ DC1 dendritic cells were added to a transwell membrane placed in the culture well (dashed line). Data shown are gated on CD4-positive cells and are representative of 4 experiments. (<i>3C</i>) 1.25×10⁵ T_regs were co-cultured with 2.5×10⁵ CFSE-labeled responders alone for 5 days. 1×10⁵ DC1 dendritic cells were added to a transwell membrane placed in the culture well. Data shown are gated on CD4-positive cells (<i>N</i> = 2). (3<i>D</i>) The number of mitoses per 10⁴ cells is summarized for CD4-positive responder cells in the presence of T_regs and iDC alone, iDC with DC1 added to the Transwell membrane, and DC1 alone. (<i>3E&F</i>) 1.25×10⁵ T_regs were co-cultured with 2.5×10⁵ CFSE-labeled responders and 1×10⁵ DC1 dendritic cells in the presence (dashed line) or absence (solid line) of neutralizing anti-IL-12 (<i>3E</i>) or anti-IL-6 (<i>3F</i>) antibodies (5 µg/mL). Data shown are gated on CD4-positive cells and are representative of at least three experiments.