Male LDLr−/− mice 10–12 weeks of age were fed a Western-type diet containing 15% cocoa butter and 0.25% cholesterol 2 weeks prior to collar Selleck Compound C placement. Atherosclerosis was induced by placement of collars (0.3 mm, Dow Corning, Midland, Michigan) around the carotid arteries as previously described [20]. Hereafter, the mice were fed a Western-type diet for 8 more weeks. Total cholesterol levels during the experiment were quantified spectrophotometrically using an enzymatic procedure (Roche Diagnostics, Germany). Precipath standardized serum (Boehringer, Germany) was used as an internal standard. The murine fibroblast cells were used as target cells and were co-transfected

with pcDNA3.1-IL-15 and pcDNA3.1-eGFP using ExGen500 (Fermentas, Germany) according to the manufacturer’s protocol. 24 h after selleck compound transfection, 106 spleen cells isolated from IL-15 vaccinated or control vaccinated mice were added to the target cells. 24 h later, cells were fixed using FormalFixx (3.7%, Thermo Shandon, Pittsburgh, PA), and the number of GFP-fluorescent cells per well

was determined. Carotid arteries were removed for analysis as described by Von der Thüsen et al. [20]. The arteries were embedded in OCT compound (TissueTek; Sakura Finetek, The Netherlands). Cryosections of 5 μm were made proximally of the collar occlusion and stained with hematoxylin (Sigma Diagnostics, MO) and eosin (Merck Diagnostica, Germany). Corresponding sections on separate slides were stained

immunohistochemically for macrophages using an antibody against a macrophage-specific antigen (MoMa-2, Research Diagnostics Inc.). Quantification of the staining Oxygenase was performed by using a Leica DM-RE microscope and Leica Qwin Imaging software (Leica Ltd., Germany). Peripheral Blood Mononuclear Cells (PBMC) were isolated after orbital bleeding using Lympholyte (Cedarlane, Canada) as described in the manufacture’s protocol. Spleens were dissected and single cell suspension was obtained by passing the spleen through a 70 μm cell strainer (Falcon, The Netherlands). Leukocytes were purified using Lympholyte. Cells were stained with FITC-conjugated anti-mouse CD8 (0.125 μg/sample, Pharmingen) and PE-conjugated anti-mouse CD69 (0.125 μg/sample, eBioscience). For the staining of surface bound IL-15, the leukocytes were stained with biotinylated anti-mouse IL-15 (R&D systems) and PE-conjugated streptavidin (BD Pharmingen) and analyzed by flowcytometry on a FACSCalibur. All data was analyzed with CELLQuest software (BD Bioscience, The Netherlands). All data are expressed as means ± SEM. The two-tailed student’s t-test was used to compare individual groups of mice or cells. When indicated, a Mann–Whitney test was used to analyze not normally distributed data. P values of <0.05 were considered significant. The spleens of LDLr−/− mice were collected at different time points after the start of the Western-type diet feeding and mRNA expression of IL-15 was quantified.