Figure 2.

LF 15-0195-treated dendritic cells inhibit antigen-specific T-cell responses. (a) LF-treated dendritic cells (DC) inhibit anti-keyhole limpet hemocyanin (KLH) T-cell responses. Day 4 bone-marrow-derived DC cultured in granulocyte-macrophage colony-stimulating factor (10 ng/ml) and IL-4 (10 ng/ml) were treated with different concentrations of LF (0.1, 1, and 10 μg/ml) or PBS alone. On day 7 of culture, 10 μg/ml KLH was added to the cells for 24 hours and then cells were activated with TNFα (10 ng/ml) and lipopolysaccharide (10 ng/ml). On day 9 of DC culture, 5 × 10⁵ cells/mouse were injected intraperitoneally into syngeneic BALB/c mice. After 10 days, the mice were sacrificed and T cells from lymph nodes were isolated. A KLH-specific recall response was determined by the proliferation, as described in Materials and methods. *P < 0.05 versus nontreated control DC. (b) and (c) LF-treated DC-induced immune suppression is antigen specific. DC were cultured, treated with LF, pulsed with type II collagen (CII) antigen, and immunized mice as described in (a). Two days prior to LF-treated DC or untreated control DC immunization, the mice were immunized with 10 μg KLH subcutaneously. Ten days after immunization, lymph node cells were harvested and proliferated in vitro in the presence of CII (b) and KLH (c), respectively, at the indicated concentrations. Results represent one of three experiments. *P < 0.05 versus nontreated control DC. cpm, counts per minute.