BIOT 307: MOLECULAR IMMUNOLOGY. Cells and Organs March 7-9, 2011. IMMUNE CELLS. B lymphocytes T “ NK Macrophages Dendritic Cells. Antigen Specific. Antigen-presenting cells (APCs), non-specific. characteristic (See Fig. 2-2) antigen receptors - B, T, NK
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Cells and Organs
March 7-9, 2011
Antigen-presenting cells (APCs), non-specific
DEVELOPMENT OF IMMUNE CELLS
IL1-7, CSF – G, GM, M
TH , TC subsets
B cell subsets
Structural and functional changes
Also T-independent activation
Thymic stromal cells and APCs (macrophages and DCs) MHC recognition of MHC I/II molecules
MORE NOTES FOR PREVIOUS PAGE: Memory T cell, confer long-term immunity.
Tregs CD4+CD25+, some of which are generated from the thymus, are thought to suppress CD4+ and CD8+ T cells
B-cell development in the bone marrow:
common lymphocyte precursors (CLP) immature B lineage-committed cells (pro-B) Ig heavy chain gene rearrangements in pre-B cell stage -->naïve mature B cells leave bone marrow w/ the IgM receptor secondary lymphoid tissues, where they encounter antigens and are activated; secrete IgM and may isotype switch to IgG. Some differentiate into plasma cells, secreting antigen-specific IgG antibodies essential for long-term immune response.
NOTES FOR PREVIOUS PAGE: Schematic representation of T cell development. T cells originate from the common lymphoid progenitor cells in the bone marrow. They migrate as immature precursor T cells via the bloodstream into the thymus, which they populate as thymocytes. The thymocytes go through a series of maturation steps including distinct changes in the expression of cell surface receptors, such as the CD3 signaling complex (not shown) and the coreceptors CD4 and CD8, and the rearrangement of their antigen receptor (T cell receptor, TCR) genes. More than 98% of the thymocytes die during maturation by apoptosis (†), as they undergo positive selection for their TCR's compatibility with self-major histocompatibility molecules, and negative selection against those T cells that express TCRs reactive to autoantigenic peptides. In humans, the vast majority of peripheral blood T cells expresses TCRs consisting of α and β chains (αβ T cells). A small group of peripheral T cells bears an alternative TCR composed of γ and δ chains (γ/δ T cells). αβ and γδ T cells diverge early in T cell development. Whereas αβ T cells are responsible for the classical helper or cytotoxic T cell responses, the function of the γδ T cells within the immune system is largely unknown. αβ T cells that survive thymic selection lose expression of either CD4 or CD8, increase the level of expression of the TCR, and leave the thymus to form the peripheral T cell repertoire.Skapenko et al. Arthritis Research & Therapy 2005 7(Suppl 2):S4 doi:10.1186/ar1703
Ag-specific effector cell clones