Lineage-specific B7h transgene expression on B cells from B-B7hTg mice after activation and on dendritic cells from DC-B7hTg mice. B7h transgene expression in B-B7hTg and DC-B7hTg mice was assessed by flow cytometry on the B7h−/− background to avoid contribution from endogenous B7h. B7h staining is shown (solid line) after gating on the indicated cell subsets, with background staining of B7h−/− controls (dashed line). (A) B7h transgene expression on resting splenocytes was assessed using CD11c, B220, and Thy1 as markers for DCs, B cells and T cells, respectively. To assess transgene expression on activated B and T cells, purified resting splenic B and T cells were activated for 16 hours with anti-IgM F(ab’)2 or PMA and ionomycin, respectively. (B) B7h and B7.2 expression were examined on splenic CD11c+ dendritic cells from naive mice, purified CD11c+ dendritic cells derived from bone marrow, and splenic CD11c+ cells purified from mice injected with Flt3-ligand-expressing B16 cells, either directly ex vivo or after 16 hours of treatment with LPS. For B7.2 analysis, dashed lines represent the background staining of a non-specific isotype control antibody. (C) B7h staining of purified resting splenic B cells, gated B220+, was assessed before and after 3 days of stimulation with anti-IgM F(ab’)2. B7h staining of B220+IgDneg-GL7+Fas+ germinal center B cells and IgDneg-syndecan-1+B220lo plasma B cells was assessed at day 7 in mice immunized with NP-CGG in alum.