医学免疫学英文教学课件：chapter 3 Immune System

1、1Chapter 3 Immune System2ContentsPart Central immune organs Part Peripheral immune organs Part Lymphocytes and recirculationPart Immune moleculesImmune SystemImmune organs and immune tissues Immune cells Immune molecules Immune organs:Central immune organs Peripheral immune organsPart I. Central imm

2、une organsThymus Bone marrowBursa of Fabricius: the sites of B cells maturation in birdsI. Bone marrow The bone marrow is the site of generation of all circulating blood cells in the adult, including immature lymphocytes, and is the site of B cell maturation. 1. Micro-environments in bone marrowStro

3、mal cells: reticular cells, fibroblasts, endothelial cells, macrophages.Molecules secreted by stromal cells: IL-7,etc. 2. Functions of bone marrowSites of generation of all circulating blood cells and immune cellsSites of maturation of B cellsSites of secondary humoral immune response occur.The bone

4、 marrow is the site of B cell maturationThe sites that secondary humoral immunity carries through II. Thymus The thymus is the site of T cell maturation Cells in thymusThymus stroma cells (TSC): Thymus epithelial cells(Nurse cells), Macrophages, Dendritic cells , fibroblastThymocytes: The cells migr

5、ate from the bone marrow to the thymus and then become thymocytes Micro-environments of thymus:Thymus stroma cells,especially epithelial cells(nurse cells) : cell to cell interaction.Cytokines and thymulin-like molecules (Thymosin，thymulin-， thymopoietin)produced by thymus epithelial cells: To promo

6、te the proliferation, differentiation of thymocytes.Extracellular matrix: enhance the interaction. Lymphocytes selected in thymus T cells are selected through a process of thymic education before being released into the peripheral lymphoid organs as mature lymphocytes. Positive selection (recognize

7、MHC) Negative selection (no response to self-Ag) Functions of thymus:Sites of T cell maturation. Immune regulation: cytokines and thymulin-like molecules (Thymosin，thymulin-，thymopoietin ).Barrier function. Part II Peripheral lymphoid organThe sites where mature T and B cells take up their residence

8、. The sites where adaptive immune responses to foreign antigens are initiated and developed. Lymph node SpleenSkin or Mucosal associated lymphoid tissueI. Lymph node ( LN) Lymph nodes are the organs in which adaptive immune responses to lymph-borne antigens are initiated. 1. Structure:Cortex:Lymphoi

9、d follicle ( Thymus-independent area)Paracortical area (Thymus-dependent area)Medulla: medulla cords: T cell, B cell, macrophage and plasma cells medulla sinusT cells:75%; B cells:25%2. Functions of lymph nodeFilter and eliminate foreign antigen.Sites of immune response.Participate in lymphocyte rec

10、irculation. II. Spleen The spleen is the major site of immune responses to blood-borne antigens.Structure:White pulpRed pulpWhite pulp T cell area: contain T cells, dendritic cell and macrophage. B cell area: lymphoid follicles. Red pulp: cellular cords: B cells, plasma cells and macrophage, DC.veno

11、us: blood T cells:35-50%;B cells:50-65%2. Functions: 1) Site of T and B cells reside. 2) Undergo immune response. 3) Produce IFN, complement. 4) Filter the blood.III. Skin and mucosal-associated lymphoid tissue The skin and mucosal surfaces of the gastrointestinal and respiratory tracts are colonize

12、d by lymphocytes and APCs that initiate immune responses to ingested and inhaled antigens.Skin-associated lymphoid tissue (SALT)Mucosal-associated lymphoid tissue (MALT)The constitution of MALTGut-associated lymphoid tissue, GALTNasal-associated lymphoid tissue, NALT Bronchial-associated lymphoid ti

13、ssue, BALT submucosaStructure of MALT2. Functions of MALTLocal immunity in mucosal Site of immune responseParticipate in the effector stagePart III Lymphocytes and recirculation of lymphocytes 1. Immune cellsImmunocytes: cells that participate in immune response or relate to immune response.Lymphocy

14、tes, monocytes and macrophages2. Recirculation of lymphocytes Lymphocyte recirculation is the process by which lymphocytes continuously move between sites throughout the body through blood and lymphatic vessels, and it is critical for the initiation and effector phases of immune responses. Lymphocyt

15、es recirulationBloodparacortex of Lymphoid nodeThoracic ductHEVHoming of lymphocytes: the process by which particular subsets of lymphocytes selectively enter some tissues but not others is called lymphocyte homing. lymphocyte homing receptor on T lymphocyte and ligand (vascular addressin) on endoth

16、elial cell) Homing of T cells It enables the limited number of lymphocytes in an individual that are specific for a particular foreign antigen to search for that antigen.It ensures that particular subsets of lymphocytes are delivered to the particular tissue where they are required for adaptive immu

17、ne responses. Fulfill lymphocyte tissues with circulated lymphocytes.Recirculation of memory cells promote secondary immune responses efficiently. Significance of lymphocyte recirculationPart IV Immune moleculesCell surface molecules (membrane) markers molecules mediated cell-to-cell interactionEffector molecules (soluble mediators) cytokines complements,