TAILIEUCHUNG - Ebook Kuby immunology (7/E): Part 2
Part 2 book “Kuby immunology” has contents: T-Cell activation, diferentiation, and memory, B-Cell activation, diferentiation, and memory generation, efector responses - Cell-And antibody - mediated immunity, . and other contents. | c11T-CellActivation,Differentiation, Page 357 12/20/12 5:03 PM user-t044 /Volumes/203/MHR00209/siL52070/disk1of1/0071052070 11 T-Cell Activation, Differentiation, and Memory T he interaction between a naïve T cell and an antigen-presenting cell (APC) is the initiating event of the adaptive immune response. Prior to this, the innate immune system has been alerted at the site of infection or tissue damage, and APCs, typically dendritic cells, have been activated via their pattern recognition receptors. These cells may have engulfed extracellular (or opsonized intracellular) pathogens, or they may have been infected by an intracellular pathogen. In either case, they have processed and presented peptides from these pathogens in complex with surface MHC class I and class II molecules, and have made their way to a local (draining) lymph node and/or the spleen. The APCs have taken up residence in the T-cell zones of the lymph node or spleen to join networks of other cells that are continually scanned by roving naïve CD8 and CD4 T cells, which recognize MHC class I-peptide and MHC class IIpeptide complexes, respectively. We have seen that each mature T cell expresses a unique antigen receptor that has been assembled via random gene rearrangement during T-cell development in the thymus (Chapter 9). Because developing T cells undergo selection events within the thymus, each mature, naïve T cell is tolerant to self antigens, and restricted to self-MHC (Chapter 9). Some naïve T cells have committed to the CD8 cytotoxic T-cell lineage, some to the CD4 helper T-cell lineage. When a naïve CD8 or CD4 T cell binds tightly to an MHC-peptide complex expressed by an activated dendritic cell, it becomes activated by signals generated through the TCR (see Chapter 3). These signals, in concert with signals from other factors that we will describe below, stimulate the T cell to proliferate and differentiate into an effector cell. As you know, naïve CD8 T cells .
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