医学免疫学英文版课件：Chapter 3 immnune system

1、MEDICAL IMMUNOLOGYChapter 3Immune SystemImmune organs and immune tissues Central immune organs (primary lymphoid organs) Peripheral immune organ (secondary lymphoid organs) Immunocytes Lymphocytes (T, B cells and NK cells) APC (M, DC, B cells) Other cells (neutrophil, basophil, eosinophil etc.)Immun

2、e molecules Antibody, Complement, Cytokine, adhesion molecules and MHC molecules etc.Immune organsCentral immune organs (primary lymphoid organs) Thymus Bone marrow/ Bursa of Fabricius Peripheral immune organ (secondary lymphoid organs) Lymph nodes Spleen Skin and Mucosal associated lymphoid tissueI

3、 Central Immune organs Central Immune Organs are the sites of generation, differentiation, development and maturation of immunocytes. Thymus: differentiation and maturation of T cells Bone marrow: generation of all immnocytes and maturation of B cells in humanBursa of Fabricius: the site of B cells

4、maturation in birds The thymus is the site of T cell differentiation, development and maturation. DiGeorge syndrome: mutations in genes required for thymus development.Nude mice: mutation in a transcriptional factor caused a failure of differentiation of certain types of epithelial cells that are re

5、quired for normal development of thymus. 1. ThymusThe structure of Thymus Cortex: thymus epithelial cells, thymocyte, macrophageMedulla： thymus epithelial cells, thymocytes and macrophages, hassals corpuscle/thymic corpuscleThymus Thymus Thymus microenvironmentThymus stroma cells (TSC) Thymus epithe

6、lial cells (TEC), Fibroblast, Macrophages, Dendritic cells TEC: Secret thymus hormones and cytokines. Interaction between cells by direct contact.Extracellular matrixActive substance in local sites ThymusFunctions of Thymus Development and differentiation of T lymphocytes TSC interact with thymocyte

7、s directly by adhesion molecules.TSC secrete various cytokines and thymus hormones.Thymocytes secrete various cytokines. Immune regulation of the thymus Barrier function of the thymus Thymus2. Bone marrow The bone marrow is the site of generation of all circulating blood cells in the adult, includin

8、g immature lymphocytes, and is the site of B cell maturation. Functions of bone marrowThe site of generation of all immunocytes and blood cellsThe site of differentiation and maturation of B cellsThe site of humoral immune response of B cell, specifically in secondary immune response. 3. Bursa (Burs

9、a of Fabricius)Specific immune organs in birdsThe site of differentiation and proliferation of B cells in birds. Peripheral lymphoid organ The site where lymphocytes locate, response to foreign antigens, produce specific antibody and sensitized T lymphocytes. Lymph node SpleenMucosal associated lymp

10、hoid tissue (MALT) Skin associated lymphoid tissue (SALT)1. Lymph node ( LN) 500600Structure of LNFunctions of lymph nodesThe site of lymphocytes residence (75%: T cell, 25%: B cell)The site of immune response Take part in lymphocyte recirculationFilter and eliminate foreign antigens2. Spleen The sp

11、leen is the major site of immune responses to blood-borne antigens.Functions of spleenThe site of immunocytes residence (40%: T cell, 60%: B cell)The site of immune response.Produce some active substances, such as complement, et al.Function of filtration.3. SALT The skin contains a specialized cutan

12、eous immune system consisting of lymphocytes and APCs (such as Langerhans cell) 4. MALT The mucosal surfaces of the gastrointestinal and respiratory tracts, like the skin, are colonized by lymphocytes and APCs that initiate immune responses to ingested and inhaled antigens.Composition of MALT Gut-as

13、sociated lymphoid tissue (GALT)NALT (N:nasal)BALT (B:bronchial) Functions of MALT and SALTThe first line of defense against foreign antigen. The site of immune response.Participate in delayed hypersensitivity.The site of sIgA secretion Homing and recirculation of lymphocytesHoming of lymphocytes: th

14、e process by which particular subsets of lymphocytes selectively enter and residue in peripheral lymphoid organs. (homing receptors and ligand on endothelial cell) Lymphocyte recirculation: is the process lymphocytes circulate repeatedly among blood, lymph, lymphoid organs and tissues. Promote lymphocytes to contact with antigen throughout the body.Promote effector cells migrate to inflammation sites rapidly.Promote lymph tissue acquire supplement of new lymphocytes from circulatory pools. Memory cells can participate in recirculation and secondary immune r