D as follows; increase in MFI = [(uptake at 37uC)/ (uptake at 4uC)6100]. To selectively inhibit macropinocytosis and other actin-dependent mechanisms, HBEC were pre-incubated for 15 min at 37uC with cytochalasin D (CCD; 10 mM; Sigma).Conjugation assaysThe ability of HBEC to form long-lasting conjugates with T cells was assessed using an in vitro conjugation assay. Briefly, CD4+ and CD8+ T cells were isolated from PBMC using EasySepH. Isolated T cells and trypsinated HBEC were then labeled with the membrane-labeling agents, PKH26 (red) and PKH67 (green) respectively (Sigma). 16105 T cells and 16105 HBEC were coincubated for 30 min at 37uC prior to flow cytometric analysis. Conjugates were deemed to be positive for both PKH26 and PKH27.Materials and Methods Ethics StatementThe blood samples used in this study are from anonymous donors from the Australian Red Cross Blood Bank. Protocol was approved by the University of Sydney Human Ethics Committee (Approval #10218).In vitro T cell MedChemExpress Z-360 proliferation assaysHBEC were cultured to confluence in 24 well tissue culture plates (Corning). Cells were either left under resting conditions or stimulated with a combination of 10 ng/ml TNF and 50 ng/ml IFNc for 18 h. 16105 buy LIMKI-3 CFSE-labeled PBMCs were added per well with the following conditions; PBMC alone, 0.3 mg/ml aCD3 (eBioscience; Clone HIT3a) or 0.3 mg/ml aCD3+1 mg/ml aCD28 (eBioscience; Clone CD28.2). The co-cultures were incubated for 6 days at 37uC. After 6 days in culture the nonadherent cells were then collected for staining and flow cytometric analysis. Non-adherent cells were stained with PE conjugated antihuman CD4 (eBioscience; Clone OKT4) and PE-Cy5 anti-human CD8a (Biolegend; Clone HIT8a) prior to multi-colour flow cytometric analysis. T cell proliferation was then quantitated with the parameters set to a log scale. A forward scatter vs FL1 was used to gate on the PBMC population that was positive for CFSE. This gated population was then used to differentiate between CD4+ T cells and CD8+ T cells. CFSE histograms depict the number of events (y-axis) and the fluorescence intensity (x-axis) with proliferating cells displaying a progressive 2-fold loss in fluorescence intensity following cell division, indicative of proliferating cells. To determine whether cell contact is necessary for EC to support T cell proliferation, the use of transwells was employed. 16105 PBMC/well were placed in 0.4 mm transwells (Costar) and co-culture with HBEC performed as outlined above.Cells and cell cultureImmortalised human brain microvascular hCMEC/D3 endothelial cells (HBEC) [18] were cultured in EBM-2 medium (Lonza CC-3156). Cells were grown on plates pre-coated with rat tail collagen type I (BD Biosciences). Cytokine activation of HBEC was performed by treating the cells with 10 ng/ml TNF or 50 ng/ ml IFNc (Peprotech) for 18 h.Human PBMC preparationPBMC were separated either from leukopacks or from heparinized venous blood by conventional Ficoll gradient and brought to 26106/ml in complete medium. PBMC were frozen in 10 DMSO in FCS and stored in liquid nitrogen. PBMC were thawed and washed twice in cold medium before use in assays.T cell isolation and CFSE stainingCD4+ and CD8+ T cells were isolated from freshly thawed PBMCs using an EasysepH (Stemcell Technologies) negative selection kit according to the manufacturer’s instructions. For labeling both isolated T cells and whole PBMCs with Carboxyfluorescein succinimidyl ester (CFSE; Invitrogen), cells (at a.D as follows; increase in MFI = [(uptake at 37uC)/ (uptake at 4uC)6100]. To selectively inhibit macropinocytosis and other actin-dependent mechanisms, HBEC were pre-incubated for 15 min at 37uC with cytochalasin D (CCD; 10 mM; Sigma).Conjugation assaysThe ability of HBEC to form long-lasting conjugates with T cells was assessed using an in vitro conjugation assay. Briefly, CD4+ and CD8+ T cells were isolated from PBMC using EasySepH. Isolated T cells and trypsinated HBEC were then labeled with the membrane-labeling agents, PKH26 (red) and PKH67 (green) respectively (Sigma). 16105 T cells and 16105 HBEC were coincubated for 30 min at 37uC prior to flow cytometric analysis. Conjugates were deemed to be positive for both PKH26 and PKH27.Materials and Methods Ethics StatementThe blood samples used in this study are from anonymous donors from the Australian Red Cross Blood Bank. Protocol was approved by the University of Sydney Human Ethics Committee (Approval #10218).In vitro T cell proliferation assaysHBEC were cultured to confluence in 24 well tissue culture plates (Corning). Cells were either left under resting conditions or stimulated with a combination of 10 ng/ml TNF and 50 ng/ml IFNc for 18 h. 16105 CFSE-labeled PBMCs were added per well with the following conditions; PBMC alone, 0.3 mg/ml aCD3 (eBioscience; Clone HIT3a) or 0.3 mg/ml aCD3+1 mg/ml aCD28 (eBioscience; Clone CD28.2). The co-cultures were incubated for 6 days at 37uC. After 6 days in culture the nonadherent cells were then collected for staining and flow cytometric analysis. Non-adherent cells were stained with PE conjugated antihuman CD4 (eBioscience; Clone OKT4) and PE-Cy5 anti-human CD8a (Biolegend; Clone HIT8a) prior to multi-colour flow cytometric analysis. T cell proliferation was then quantitated with the parameters set to a log scale. A forward scatter vs FL1 was used to gate on the PBMC population that was positive for CFSE. This gated population was then used to differentiate between CD4+ T cells and CD8+ T cells. CFSE histograms depict the number of events (y-axis) and the fluorescence intensity (x-axis) with proliferating cells displaying a progressive 2-fold loss in fluorescence intensity following cell division, indicative of proliferating cells. To determine whether cell contact is necessary for EC to support T cell proliferation, the use of transwells was employed. 16105 PBMC/well were placed in 0.4 mm transwells (Costar) and co-culture with HBEC performed as outlined above.Cells and cell cultureImmortalised human brain microvascular hCMEC/D3 endothelial cells (HBEC) [18] were cultured in EBM-2 medium (Lonza CC-3156). Cells were grown on plates pre-coated with rat tail collagen type I (BD Biosciences). Cytokine activation of HBEC was performed by treating the cells with 10 ng/ml TNF or 50 ng/ ml IFNc (Peprotech) for 18 h.Human PBMC preparationPBMC were separated either from leukopacks or from heparinized venous blood by conventional Ficoll gradient and brought to 26106/ml in complete medium. PBMC were frozen in 10 DMSO in FCS and stored in liquid nitrogen. PBMC were thawed and washed twice in cold medium before use in assays.T cell isolation and CFSE stainingCD4+ and CD8+ T cells were isolated from freshly thawed PBMCs using an EasysepH (Stemcell Technologies) negative selection kit according to the manufacturer’s instructions. For labeling both isolated T cells and whole PBMCs with Carboxyfluorescein succinimidyl ester (CFSE; Invitrogen), cells (at a.