Polymorphonuclear neutrophils (PMN) mediate early immunity to infection but can also cause host damage if their effector functions are not controlled. Their lack or dysfunction is associated with severe health problems and thus the analysis of PMN physiology is a central issue. One prerequisite for PMN analysis is the availability of purified cells from primary organs. While human PMN are easily isolated from peripheral blood, this approach is less suitable for mice due to limited availability of blood. Instead, bone marrow (BM) is an easily available reservoir of murine PMN, but methods to obtain pure cells from BM are limited. We have developed a novel protocol allowing the isolation of highly pure untouched PMN from murine BM by negative immunomagnetic isolation using a complex antibody cocktail. The protocol is simple and fast (∼1 h), has a high yield (5–10*106 PMN per animal) and provides a purity of cells equivalent to positive selection (>80%). Most importantly, cells obtained by this method are non-activated and remain fully functional in vitro or after adoptive transfer into recipient animals. This method should thus greatly facilitate the study of primary murine PMN in vitro and in vivo.
T cells are key mediators of cell-mediated immunity. Their functions and proliferation result from T cell-specific receptor signaling (TCR/CD28) that activates the NF-κB, NFAT, Ras-MAPK, and PI3K-Akt pathways. Their development and activation also involve a complex array of signaling pathways that regulate gene expression networks, including signaling of mTOR, Notch, Wnt, Hedgehog, TGF-β, and toll-like receptors. Furthermore, recent discoveries have provided two molecular hallmarks of potential generality: miRNA patterns and polycomb-mediated epigenetic reprogramming, which can strongly coordinate the balance between molecular networks in lymphocytes. Their deregulation apparently causes T cell disorders, such as T cell acute lymphoblastic leukemia (T-ALL), and human T cell leukemia virus (HTLV-1)-induced adult T cell leukemia (ATL). This review continues with a description of our understanding of crosstalk among the signaling pathways, which contribute to the highly orchestrated development of T cell fate specification under both normal physiological and pathological conditions.
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