Ns and present them on MHC class I and II molecules

Ns and present them on MHC class I and II molecules at their apical surface. The vascular EC that separate the blood stream from the brain parenchyma is referred to as the blood brain barrier (BBB). The BBB provides both anatomical and physiological protection for the central nervous 1379592 system, regulating the entry of many substances and blood borne cells into the nervous tissue. There is increasing evidence of interactions between T cells and brain endothelium in diseases such as multiple sclerosis, cerebral malaria (CM) and viral neuropathologies. Of particular note, the diameter of microvessels, where thepathology is seen during CM, is smaller than the size of activated lymphocytes; therefore the latter physically “brush” the EC surface and can thus interact very closely. Additionally, during CM, both T cells and monocytes are arrested in brain microvessels [2] and we recently Dimethylenastron supplier demonstrated that brain EC can display antigens from infected erythrocytes on their surface, thereby possibly initiating immune responses [3]. MHC expression, which is the primary requirement for APC activity has been demonstrated on EC with both MHC I and II upregulated following cytokine treatment [4?]. Moreover, EC may also qualify as APCs due to the secretion of cytokines, particularly GM-CSF [7,8]. Some studies using MHC matched donors supports the model that cultured human EC are able to present antigen and thus re-activate primed CD4+ T cells [9?1]. However, EC are ?specifically able to re-stimulate T cells, but not to prime naive T cells, which is a hallmark of “professional” APCs such as dendritic cells [12?4]. Additional studies using co-cultures of MHC-mismatched EC and T cells resulted in the activation of both CD4+ and CD8+ T cells suggesting that EC are able to present alloantigens [15,16]. The body of evidence supporting the role of EC as APC (reviewed in [17]) led us to investigate the capacity of brain microvascular EC to act as APC and modulate T cell activation and proliferation. Here we confirm and expand on previous data [18] and show that immortalised human brain microvascular hCMEC/D3 endothelial cells (HBEC) express MHC II and theBrain Endothelium and T Cell Proliferationco-stimulatory molecules CD40 and ICOSL following cytokine stimulation. We also demonstrate that HBEC were able to take up fluorescently labeled antigens via macropinocytosis and clathrin coated pits. Moreover in our peripheral blood mononuclear cell (PBMC)/HBEC co-cultures, HBEC support and promote the proliferation of both CD4+ and CD8+ T cells suggesting that the brain endothelium is able to process and present antigens to allogeneic T cells. Finally, we were able to demonstrate that the interaction between T cells and HBEC occurs in a 2-way fashion as the expression of MHC II on HBEC was significantly increased following co-culture with PBMC. Combined, our data indicates that EC can act as semi-professional APC, which has important implications for the presentation of antigens to T cells, resulting in the activation of the effector T cell response in neuroinfectious diseases, particularly CM.with either 1 mg/ml Fluorescein isothiocyanate (FITC)-Ovalbumin (OVA) or Lucifer Yellow (CAL 120 Invitrogen) at 37uC for 45 min and washed three times with PBS. Results are expressed as the percentage increase in mean fluorescence intensity (MFI), which subtracts any fluorescence detected by nonspecific surface binding after incubation on ice. The percentage increase in MFI is calculate.Ns and present them on MHC class I and II molecules at their apical surface. The vascular EC that separate the blood stream from the brain parenchyma is referred to as the blood brain barrier (BBB). The BBB provides both anatomical and physiological protection for the central nervous 1379592 system, regulating the entry of many substances and blood borne cells into the nervous tissue. There is increasing evidence of interactions between T cells and brain endothelium in diseases such as multiple sclerosis, cerebral malaria (CM) and viral neuropathologies. Of particular note, the diameter of microvessels, where thepathology is seen during CM, is smaller than the size of activated lymphocytes; therefore the latter physically “brush” the EC surface and can thus interact very closely. Additionally, during CM, both T cells and monocytes are arrested in brain microvessels [2] and we recently demonstrated that brain EC can display antigens from infected erythrocytes on their surface, thereby possibly initiating immune responses [3]. MHC expression, which is the primary requirement for APC activity has been demonstrated on EC with both MHC I and II upregulated following cytokine treatment [4?]. Moreover, EC may also qualify as APCs due to the secretion of cytokines, particularly GM-CSF [7,8]. Some studies using MHC matched donors supports the model that cultured human EC are able to present antigen and thus re-activate primed CD4+ T cells [9?1]. However, EC are ?specifically able to re-stimulate T cells, but not to prime naive T cells, which is a hallmark of “professional” APCs such as dendritic cells [12?4]. Additional studies using co-cultures of MHC-mismatched EC and T cells resulted in the activation of both CD4+ and CD8+ T cells suggesting that EC are able to present alloantigens [15,16]. The body of evidence supporting the role of EC as APC (reviewed in [17]) led us to investigate the capacity of brain microvascular EC to act as APC and modulate T cell activation and proliferation. Here we confirm and expand on previous data [18] and show that immortalised human brain microvascular hCMEC/D3 endothelial cells (HBEC) express MHC II and theBrain Endothelium and T Cell Proliferationco-stimulatory molecules CD40 and ICOSL following cytokine stimulation. We also demonstrate that HBEC were able to take up fluorescently labeled antigens via macropinocytosis and clathrin coated pits. Moreover in our peripheral blood mononuclear cell (PBMC)/HBEC co-cultures, HBEC support and promote the proliferation of both CD4+ and CD8+ T cells suggesting that the brain endothelium is able to process and present antigens to allogeneic T cells. Finally, we were able to demonstrate that the interaction between T cells and HBEC occurs in a 2-way fashion as the expression of MHC II on HBEC was significantly increased following co-culture with PBMC. Combined, our data indicates that EC can act as semi-professional APC, which has important implications for the presentation of antigens to T cells, resulting in the activation of the effector T cell response in neuroinfectious diseases, particularly CM.with either 1 mg/ml Fluorescein isothiocyanate (FITC)-Ovalbumin (OVA) or Lucifer Yellow (Invitrogen) at 37uC for 45 min and washed three times with PBS. Results are expressed as the percentage increase in mean fluorescence intensity (MFI), which subtracts any fluorescence detected by nonspecific surface binding after incubation on ice. The percentage increase in MFI is calculate.