Plates blocked with PBS containing 10% FBS before 50 μL supernatants were added, and the incubated overnight at 4°C. After extensive washing, plates were incubated with a biotinylated anti-IFN-γ detection antibody. Plates were developed using avidin-peroxidase and 2-2′-azino-bis(3-ethyl-benzthiazoline-6-sulfonic acid) substrate (Sigma-Aldrich). OD405 was measured, and cytokine levels determined against a recombinant protein standard. All antibodies were purchased form BD Pharmingen. IFN-γ–producing cells were enumerated from splenocyte

CT99021 molecular weight populations isolated from immunized mice by cellular ELISPOT assay 47. Briefly, splenocytes (5×106 cells/mL) were cultured for 48 h in 24-well plates either with B5, B1 (10 μg/mL) or medium alone. Millititer HA nitrocellulose plates (Millipore) were coated overnight at 4°C with anti–IFN-γ. After blocking coated plates, antigen-stimulated cells were added at graded concentrations for 24 h at 37°C. learn more The wells were then incubated with biotin-conjugated anti–IFN-γmAb followed by incubation with avidin peroxidase (Vector Laboratories). Spots were developed by the addition of 3-amino-9-ethylcarbazole substrate (Sigma-Aldrich) and counted using a computerized image analysis system (Ligh-tools Research) and the image analyzer program, NIH Image 1.61. Immature BM-derived DC (1×106) were pulsed with 1×106 apoptotic (Ap-T) or untreated (T) T cells, peptide (20 μg/mL) or PBS for 8–12 h. In most experiments

DC were enriched by positive selection using anti-CD11c microbeads (Miltenyi) all and treated with activation modulators (for example, LPS (Sigma)) for 4–12 h CD11c+. DC were disabled (irradiated (3000 rad) or glutaraldehyde-fixed) and incubated with T responder cells (2×104/well) for the duration of the assay at 37°C in 5% CO2. For experiments analyzing the effect of antigen processing/presentation blockade, inhibitors

were first added to BM-derived DC for duration of 2 h – Concanamycin A (10–100 nM). DC were then washed and pulsed with peptide or apoptotic T cells for a total of 8 h (the final 4 h in the presence of LPS (1 μg/mL)). DC were positively selected using anti-CD11c microbeads (Miltenyi), and glutaraldehyde-fixed, before co-culturing with responder T cells. For IFN-γ secretion analysis, supernatants were harvested at 48 h. T-cell proliferation was measured by 3H-thymidine incorporation at 72 h. The desired number T cells were incubated in complete medium 4–12 h at 37°C in 5% CO2 in the presence of 5 μg/ml anti-Fas antibody (BD Pharmingen). To determine apoptosis induction 1×105 T cells in 100 μL buffer were stained with 10 μL/mL Annexin V FITC (BD Pharmingen). By flow cytometry apoptosis induction was confirmed using two parameters: (i) an anti-clockwise shift of the T-cell population in the forward versus side scatter dot plot, and (ii) a significant right shift of the peak on the FL1 histogram axis – indicating Annexin V staining.