JP 01 - Immuno Summary

JP 01 - Immuno Summary - Immunology Overview Points to...

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Immunology Overview Points to consider: Innate vs. adaptive immunity Complement Neutrophils vs Macrophages vs NK cells T-cells vs. B-cells Lineage Maturation and activation of each cell type Signaling, including different signals, receptors, adapters, and downstream results 1
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Lecture 2 – Innate Immunity 1: Cells, Pattern Recognition, and Receptor Signaling Jim Mahoney, Ph.D. Innate (immediate, broad, stereotypic, genomic) vs adaptive (slow, specific, somatically generated, sometimes anti-self) immunity. Innate is evolutionarily older than adaptive (only exists in vertebrates after jawed fishes). All circulating blood cells of all types come from pluripotential hematopoietic stem cells (PHSC) in bone marrow and fetal liver. Macs, PMNs, basos, eosinos are all derived from the myeloid progenitor (downstream of PHSC). T and B cells are from the lymphoid progenitor. Innate 1) Barrier functions include tight junctions/epithelial barrier, mucus layers, and antimicrobial peptide secretion (disrupting bacterial membranes). Antimicrobial peptides act by inserting into the bacterial membrane or by acting as chemoattractants. α-defensins are found in neutrophils and NK&B cells, especially in response to TLR and NOD activation. β-defensins are expressed in the epithelium. Histatins are in the saliva. 2) Recognition of pathogenic structures ( PAMPs , recognized by PRRs ) is done stereotypically (i.e., against structures that the pathogen needs in order to survive, such as CpG DNA, dsRNA, LPS, yeast cell wall, N-formyl-Met, etc.). 3) Effector mechanisms are recruitment, opsonization, phagocytosis, intracellular killing, and ‘sounding the alarm’. Innate Immune Cells Neutrophils (70% of WBCs), macrophages (7%), NK cells, γδ T cells. Neutrophils live for just a day, are active in acute inflammation, and kill via radical oxygen. Immature neutrophils are band cells , and high numbers of these generally indicate a bacterial infection. PMNs have azurophilic granules (lysosomes and defensins) and specific granules (complement receptors, adhesion molecules). These sentinel cells phagocytose professionally. Macrophages live for weeks/months, are active in chronic inflammation, present antigen, release cytokines, and use radical oxygen and NO to kill. Immature macrophages are called monocytes , and high circulating levels of these may indicate a viral infection. After phagocytosis, monocytes may exhibit tolerogenic or immunogenic signals. NK cells, by releasing cytotoxic granules, kill host cells that have become infected or tumor-ish. They recognize via ‘activating receptors’ (often chemokine receptors) but are inhibited by MHC-I. Finally, some γδ T cells release cytokines for inflammation. B-1 cells make natural (nonspecific) serum antibodies that target PAMPs broadly. NK T cells recognize bacterial lipids, not proteins, and release cytokines in response. PAMPs and PRRs
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This note was uploaded on 07/15/2011 for the course CHM 2120 taught by Professor Dr.flynn during the Spring '10 term at University of Ottawa.

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JP 01 - Immuno Summary - Immunology Overview Points to...

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