Immune system. Aims. Immune system. Lymphatic organs. Inflammation. Natural immune system. Adaptive immune system

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1 Aims Immune system Lymphatic organs Inflammation Natural immune system Adaptive immune system Major histocompatibility complex (MHC) Disorders of the immune system 1 2 Immune system Lymphoid organs Immune cells Immune proteins What is the immune system? The immune system is a complex of organs, cells, and circulating protein Lymphoid organs thymus spleen 3 Lymph node mucosa-associated lymphoid organ (MALT) 4 Immune cells Leukocytes or White blood cells Neutrophil Lymphocyte Lymphocyte B cells: antibody T cells: phagocytosis Eosinophil Basophil Cytotoxic T cells Helper T cells Suppressor T cells Monocyte 5 NK cells 6

2 Immune proteins Inflammation Body s local response to infection or injury Antibodies 1. Injury or bacteria entry into tissue 2. Vasodilatation of the surrounding vessels Complements 7 blood flow (hot and redness) 8 3. Filtration of protein and fluid into interstitial fluid (swelling) 4. Neutrophils and monocyte from capillaries into infected area 5. Destruction of bacteria in the tissue (pus) 6. Tissue repair 9 10 Immune system Natural immune system Innate defense mechanism Natural immune system (nonspecific) Adaptive immune system (specific) - Humoral immunity - Cell mediated immunity Non specific to any antigen genetic Surface barrier and mucosal immunity skin coughing, sneezing, ciliary action: lung 11 sticky mucous 12

3 skin secretion: acid ph saliva, tear, nasal secretion: lysozyme phagocytes neutrophil stomach: hydrochloric acid and protein digesting enzyme Cells of natural immune are: macrophages: monocytes spleen medullary sinus of lymph node phagocytes mast cells Liver: kuffer s cell natural killer cells (NK cells) eosinophil Natural killer Natural killer Large granule lymphocyte precise mechanism by which they recognized their target cells is not clear Target cells: tumor cell or virus-infected body cells kill on contact can be stimulated by interferon Eosinophil Eosinophil The least numerous of WBC in blood granule contain a protein rich in arginine residues called major basic protein cell can release killing enzyme called peroxidase and Phospholipase D Important in killing helminth (worm) infections Cell can secrete membrane penetrating protein called perforins Involve in hypersensitive reaction 17 18

4 Complement Complement A major trigger enzyme plasma system Important in killing bacteria and fungi Phagocytosis Making pore in bacterial cell membrane Help to get rid of AgAg-Ab complex Important in initiaion of the inflammatory response 19 Adaptive Adaptive immune immune system system How antigen meet T& B lymphocyte Humoral immunity Cell mediated immunity B lymphocytes and antibodies T lymphocytes acquired immunity Specific and memory Adaptive Adaptive immune immune system system Pathogens Humoral immunity Humoral immunity Antibodies B cell B lymphocytes produce from bone marrow and thymus Cellular immunity can transform to plasma cell by antigens B cell T cell Plasma cell 23 Antibodies 24

5 Antibodies Immnunoglobulin Y shape: heavy and light polypeptide chains There are 5 main classes: IgG, IgA, IgM, IgD, IgE IgG Most abundant cross from mother to baby and protect baby for months 25 IgA common in secretion eg saliva, gastric juice found in milk 26 IgM IgD primary immune response activate complement act as surface receptor on B cells IgE bound to mast cells involve in pathogenesis of allergic and helminth disease Antibody diversity Clonal selection human makes 10,000,000 different kinds of antibodies too much for genome to encode Each antibody composed of identical light and identical heavy chains Each B cell makes 1 kind of antibody Clonal selection 29 30

6 T cell Cell mediated immunity Self and non-self How immune system recognize body cell? Originate in thymus of infants Produced in bone marrow of adults T cell function Do not secrete antibodies Some attack other cells (T cytotoxic; TC) Some produce lymphokines -- molecules that regulate other white blood cell responses Specific recognition molecules: Major histocompatibilty complex (MHC) MHC (HLA) Set of molecule making up tissue type - MHC I : present endogenously synthesized antigen There are three types of MHC - MHC II : present exogenously derived protein eg bacterial products - MHC III : complement How immunity is not destroy themselves MHC mechanism Thymus T & B lymphocyte that react to body cells Will be destroyed 35 36

7 Disorders of the immune system Graft Rejection - MHC on the graft cell differ from MHC of recipient. - Cytotoxic T cells are mainly responsible for graft rejection. Donor APC Recipient T cell Recipient APC Recipient T cell - Immunosuppressive drug prevent graft rejection Transfusion reaction - ABO is the most important for transfusion reactions. Acquired immune deficiency syndrome (AIDS) - Human immunodeficiency virus (HIV) is a retrovirus. - Integrated the virus RNA into Host DNA. - ABO blood group mismatch results in hemolysis Allergy - HIV enter and live in helper T cell. - infected T cells are destroyed by normal T cells, therefore T cell reduce in amount. - Immune defense of host can not function properly. - AIDS patient dies from infections or cancers

8 Autoimmune disease - Immune attack the body s own cells and tissues which results is being damage and/or alteration function of organs For examples Multiple sclerosis myelin Myasthenia gravis acetylcholine receptor on skeletal muscle Grave s disease Thyroid stimulating hormone 43 receptor 44 Autoantibody to receptor 45