Immuno week 2
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This 4 page Class Notes was uploaded by Christine Ledingham on Thursday January 21, 2016. The Class Notes belongs to a course at Brown University taught by a professor in Fall. Since its upload, it has received 43 views.
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I'm pretty sure these materials are like the Rosetta Stone of note taking. Thanks Christine!!!
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Date Created: 01/21/16
Chapter 2: Cells, organs, microenvironments of the immune system Primary Bone marrow, thymus, regulate the development of lymphoid immune cells from immature precursors organs Secondary Spleen, lymph nodes, specialized sites in the gut and other lymphoid orgas mucosal tissues, coordinate the encounter of antigen with antigen-specific lymphocytes and their development into effector and memory cells HSC Hematopoietic stem cell, all functional blood cells originate from these, number decreases as one grows old hematopoiesis Process by which HSCs differentiate into mature blood cells. This occurs in two primary organs: bone marrow, and thymus, where T cells specifically complete their maturation Stem cells - Have the ability to self renew/regenerate - the ability to differentiate into diverse cell types (pluripotentce typically for embryonic ones tho) Progenitor cells Daughters of HSCs that go on to become commited to a particular blood cell lineage CMP Common myeloid-erythroid progenitor, HSC daughter that gives rise to all red blood cells CLP Common lymphoid progenitor, which gives rise to B lumphocyts, T lymphocytes, and NK cells. Both innate and adaptive immune response Myeloid lineage These cells are the first to respond to the presence of a pathogen granulocytes Part of innate immune system, wbcs (leukocytes) that are classified as neutrophils, basophils, mast cells, or eosinophils. Visually distinctive bc of multilobed nuclei, granules in cytoplasm contain proteins that have distinct functions. neutrophils Majority of leukocytes, circulate peripheral blood, migrate into tissues after 7-10 hrs. increase in number of circulating neutrophils=leukocytosis = indication of infection. In tissues: engulf bacteria and secrete proteins with antimicrobial effects, dominant first responders. Main components of pus chemokines Imflammatory molecules basophils Nonphagocytic granulocytes, have basophilic proteins, rare in circulation, bind to antibodies and release granules like histamines (which increase blood vessel permeability, smooth muscle activity, and activate the immune response) Mast cells Released from bone marrow as undifferentiated cells, mature after leaving the blood and entering tissues. Also have granules that contain histamine, similar to basophils eosinophils Motile phagocytic cells, less importatnt than neutrophils, most important in defense against worms, secrete cytokines that regulate B and T lymphocytes, contribute to allergy problems. APC function - phagocytic cels (monocytes, macrophages, and dendritic cells) Professional Antigen-presenting cell function, bridges between two immune systems, make contact with patogens, then communicate encounter to T lymphocytes in the lymph node. Dendritic cells Play primary role in presenting antigen to and activating naïve T cells, most effective APC, initiate the immune response this way! Start out life as antigen capture via phagocytosis and whatnot in the peripheral tissues, then do antigen presentation in lymphoid organs. monocytes 5-10% of wbcs, differentiate into tissue-resident phagocytic cells like macrophages and dendritic cells. - inflammatory monocytes: enter tissues quickly in response to infection - patrolling monocytes: crawl along blood vessels, reservoir for tissue resident monocytes in absence of infection, quell immune responses. macrophages Differentiated monocytes, can be long term tissue residents, or participate in inate immune response and undergo key changes (inflammatory macrophages, do APC and activate T cells) - osteoclasts, - microglial cells - alveolar macrophages, are all inflammatory macrophages opsonin Molecule that binds an antigen marking it for recognition by immune cells Follicular Completely different function from dendritic cells, solely dendritic cells located in lymph follicles rich in B cells, and interact with these to mature and diversify the B cells. erythrocytes Red blood cells, come from myeloid precursor, high concentrations of hemoglobin, deliver O2 to cells, anuclear in mammals, megakaryocyte Large myeloid cells, reside in bone marrow, give rise to s platelets(these do blood clots) lymphocytes Principal players in adaptive response, up to 40% of circulating wbcs and 99% of lymph cells. Different subpopulations, surface proteins used to differentiate them. Do cloning. - B cells - T cells - NK cells: natural killer cells CD Cluster of differentiation, surface proteins used to distinguish immune cells, TCR T cell receptor, antigen specific on surface of T cells BCR B cell receptor, antigen specific on surface of B cells, Effector cells Contact with antigen makes naïve lymphocytes differentiate into these, carry out specific functions to combat the pathogen Memory cells Differentiated from naïve lymphocytes, mediate a response with antigens that is quicker and greater in magnitude the second time B lymphocyte Derives from bone marrow in humans, have BCR, go (b cell) through a process called somatic hypermutation to generate antibodies of different functional classes. Activated ones can differentiate into plasma effector cells, which are highly specialized to secrete antibody. T Cells Mature in the thymus, can only recognize processed pieces of antigens bound to MHC protein molecules on cell membranes. - MHCs come in class I and class II for professional antigen presenting cells - Have two classes!!! See below: T helper cells Distinguishable by CD4 glycoproteins and recognize antigen in complex with MHC class II. Twice as many of these as Tc cells in normal humans. T cytotoxic cells Distinguishable by CD8 clygoproteins and recognize antigen in complex with MHC class I - differentiate into CTL cells: cytotoxic lymphocyte. Monitor cells in body, destroy those that have class I MHC antigen bonds Regulatory T Inhibits an immune response cell (Treg) NK cells Natural killers. Innate immune members, have cytotoxic granules, NKT cells Have TCRs and some express CD4, but do not have diverse TCRs, release large quantites of cytokines that can enhance and suppress the immune response. Their exact role is a bit vague. Stem cell Sequestered region where stromal cells differentiate niches Bone marrow Primary lymphoid organ that supports self-renewal and differentiation of hematopoietic stem cells into mature bcs. osteoblasts Cells that generate bone and control the differentiation of HSCs Endothelial Line the blood vessels and regulate HSC differentiation cells Reticular cells Send processes connecting cells to bone and blood vessels Sympathetic Control the release of hematopoietic cells from bone neurons marrow Thymus Thymus does T cell development!! thymocytes Immature t cells
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