Flow cytometry was used to verify the purity of the separated cells. To generate MoDCs, monocytes were cultured in RPMI-1640 (Gibco, Grand Island, NY) supplemented

with 10% fetal bovine serum, 0·5 mmβ-mercaptoethanol, 10% antibiotic/antimycotic (Gibco, Grand Island, NY), 10% HEPES (Gibco), 10% minimal essential medium non-essential amino acids (Gibco), 100 ng/ml of recombinant porcine (rp) IL-4 (Biosource, Camarillo, CA) and 20 ng/ml of rpGM-CSF (Biosource) for 6 days at 37° with 5% carbon dioxide. Half of the medium was changed every 3 days. The MoDCs were used between days 4 and 6, at which time non-adherent MoDCs6,23,24 were washed, counted and used in subsequent BIBW2992 molecular weight assays. To isolate BDCs, which are described as CD172+ CD14−,16,24 CD14− cells were labelled with a CD172 antibody (Serotec, Oxford, UK) and rat anti-mouse immunoglobulin G1 (IgG1) Microbeads (Miltenyi Biotec) and positively selected using MACS. The purity of CD172+ expression was consistently > 95%. CD172+

cells were rested overnight and then used in the assays. This procedure is slightly modified from Summerfield et al.,16 in which PBMCs were rested overnight and the non-adherent cells were depleted of CD3, CD8 and CD45RA, and then sorted for CD172. To isolate T cells, the CD172– population was positively sorted for CD4+ and CD8+ cells by labelling the cells with anti-CD4 (VMRD Inc., Pullmann, WA) and anti-CD8 antibody (VMRD Inc.) followed by incubation with rat anti-mouse IgG1 microbeads (MACS; Miltenyi Biotec). For stimulation with LPS, day 6 MoDCs and day 1 BDCs were cultured check details Plasmin at 1 × 106 cells/ml and stimulated with 100 ng/ml of

LPS (Escherichia coli O55:B5; Cambrex Bioscience, Walkersville, MD) for 6-hr for gene expression studies or for 24-hr for ELISA and flow cytometry. Expression of TNF-α was analysed by ELISA following an 8-hr incubation because of its early release.25 To evaluate morphology, 1 × 105 cells in medium were centrifuged at 150 g for 4 min, incubated with methanol for 5 min, air-dried and stained with Giemsa stain (Sigma, St Louis, MO) for 15–60 min. Cells were then washed with deionized water, air-dried and fixed for morphological examination by microscopy. The following anti-porcine antibodies were used for defining the cell types: CD172 (BL1H7, Serotec), CD1 (76-7-4, Southern Biotech, Birmingham, AL), CD3 (PPT3, Southern Biotech, Birmingham, AL), CD4 (74-12-4, VMRD Inc.), CD8 (PT36B, VMRD Inc.), CD14 (MIL-2, Serotec), CD16 (G7, Serotec), CD21 (BB6-11C9.6, Southern Biotech, Birmingham, AL), MHC II (K274.3G8, Serotec), MHC I (SLA-I, Serotec) and human CD152 (CTLA-4 fusion protein) (4 501-020, Ancell, Bayport, MN). FITC anti-mouse immunoglobulins IgG1, IgG2a and IgG2b (Southern Biotech) were used for detection by flow cytometry. The FITC-conjugated anti-mouse immunoglobulins IgG1, IgG2a and IgG2b (Southern Biotech) were used for detection by flow cytometry.