Synergistic Induction of Interferon α through TLR-3 and TLR-9 Agonists Identifies CD21 as Interferon α Receptor for the B Cell Response
Figure 2
Synergistic effect of ODN 2216 and poly I:C depends on positive feedback regulation of type I interferon induction via the interferon receptor.
(A) Spleen cells from cotton rats were stimulated with Concanavalin A for 72 hours and lymphoblasts purified by centrifugation on a ficoll-gradient. Subsequently, cells were stained with antisera specific for the human interferon receptor to test for crossreactive binding to cotton rat cells and analyzed by flow cytometry. Antibody specific for human interferon alpha receptor-1 (IFNAR-1) did not react with cotton rat cells (left) whereas antibody specific for human interferon alpha receptor-2 (IFNAR-2) did (right). IFNR specific antibody is shown as black line, controls as gray areas. B. IFNAR-2 antibody was added to cotton rat spleen cells. One hour later different concentrations of a combination of ODN2216 and poly I:C was added. 24 hours later supernatant was harvested and tested for the presence of type I interferon. The data is combined from two independent experiments. Significant differences were seen between cells treated with the combination of ODN2216 and poly I:C alone, or the combination of ODN2216 and poly I:C with antibody. IFNAR-1 antibody (not reactive with cotton rat cells) had no effect. C. Cotton rat spleen cells were stimulated with ODN 2216 or poly I:C, with or without the addition of recombinant cotton rat interferon alpha. (One unit equals one picogram of type I interferon.) 24 hours later supernatant was harvested and tested for the presence of type I interferon. The data is combined from two independent experiments, and significance was compared to cells without type I interferon treatment. Statistical analysis was done by ANOVA (* p<0.05, ** p<0.01, *** p<0.001).