Anti-CD48 Monoclonal antibody, clone IN59-2 [Biotin]

T helper lymphocytes become polarized upon antigen and cytokine stimuli received after their maturation in the thymus. Since the balance of Th1 and Th2 responses is critical in healthy and pathological immune responses, understanding the molecular base of T cell polarization still remained an important question. Using our Th0/Th1/Th2 hybridoma model system, we performed a comparative study on polarized Th1 and Th2 cells in terms of their membrane raft expression/composition, their TCR mediated activation signaling, and sensitivity to activation-induced cell death (AICD) using flow and image cytometric methods. We show here that the TCR stimulation induced more intense and sustained Ca2+-response in Th1 cells compared to Th2 ones correlates well with a shorter nuclear residence time of the Ca2+-dependent NFAT transcription factor in Th2 cells. In addition, NFAT translocation directly depended on lipid raft integrity/membrane cholesterol level. Expression pattern of raftophilic accessory proteins (CD4, CD59, and CD48) and lipids (GM1, cholesterol) were also different in the Th1 and Th2 hybridomas, similarly to differentiated spleen Th cells. The activation-induced, remarkably clustered and polarized membrane distribution of TCR/CD3 complex in Th1, but not in Th2 cells, together with an increased raft localization of Kv1.3 ion channels regulating the Ca2+-response, are consistent with the above properties of NFAT. Finally, the polarized Th cells, especially Th1, were more sensitive to AICD than their unpolarized Th0 precursor. These results suggest that the membrane microdomain organizationCa2+-signalingNFAT activation axis is an important determinant of polarized Th cell effector function and fate. (C) 2012 International Society for Advancement of Cytometry

M Phi comprise a heterogeneous population of cells, which contribute to host defense and maintenance of immune homeostasis. M Phi may be infected by human cytomegalovirus ( HCMV), which has evolved different strategies to subvert the immune response. In the present study, we comparatively analyzed the natural killer (NK) cell response against HCMV (TB40E)-infected proinflammatory (M1) and antinflammatory (M2) M Phi, derived from autologous monocytes, cultured in the presence of GM-CSF and M-CSF, respectively. M1 M Phi were more resistant to infection and secreted IL-6, TNF-alpha, IFN-alpha, and IL-12; by contrast, in HCMV-infected M2 M Phi, proinflammatory cytokines, IL-10, and IFN-alpha production were limited and IL-12 was undetectable. NK cell degranulation was triggered by interaction with HCMV-infected M1 and M2 M Phi at 48 h postinfection. The response was partially inhibited by specific antiNKp46, anti-DNAM-1, and anti-2B4 mAb, thus supporting a dominant role of these activating receptors. By contrast, only HCMV-infected M1 M Phi efficiently promoted NK cell-mediated IFN-gamma secretion, an effect partially related to IL-12 production. These observations reveal differences in the NK cell response triggered by distinct, HCMV-infected, monocyte-derived cell types, which may be relevant in the immunopathology of this viral infection. J. Leukoc. Biol. 90: 717-726; 2011.