Immunology PDF

Immunology By Dr. MAHA MOHAMED TINGARI Immunology:  Immunology is the science of protection against diseases.  Lymphoid tissue consist of lymphocytes which are present in many tissues ,we have two types of lymphoid tissues : Central ,Peripheral  Antigens are substances that induce an immune respo...

Immunology By Dr. MAHA MOHAMED TINGARI Immunology:  Immunology is the science of protection against diseases.  Lymphoid tissue consist of lymphocytes which are present in many tissues ,we have two types of lymphoid tissues : Central ,Peripheral  Antigens are substances that induce an immune response. immune system The immune system can be classified into:  Innate (or natural) immune system, &  Adaptive (or specific) immune system. Innate Vs. Adaptive Immune System Innate Adaptive  Rapid Non specific  Slow  Common microbe  Specific Antigen  No memory  Memory  Inherited (limited)  Somatic recombination  Not recognize self Ag  recognize self Ag  Examples:  Cellular: Lymphocytes  Humoral :AB 1\Epithelia 2\  Mechanical barrier Skin  Antimicrobial products: Saliva Sweat  Flowing fluids: Urine  Normal flora Inhibition and competition pH Cellular : a\Phagocytes MQ N B E b\Natural Killer (NK) cells 3\ Humoral :Complement Humoral B cells Immunity: activation of effector cells Plasma cells  Antibodies Cellular Immunity T cells direct removal (cytotoxic) Immune response (cytokines, antigen presenting cells, MHC system) Cells of the Immune System: 1. T-lymphocytes: 1)CD4 (helper) 2) CD8 (cytotoxic  Cellular immunity.  Induction of B-cells.  T-cells Receptors. 2. B-lymphocytes 3- Macrophages 4- Dendritic Cells 5- Natural Killer Cells The HLA system  Important in induction & regulation of the immune response. Genes on chromosome 6.  Significance of HLA system: -Important in transplantation Mismatch rejection. - Regulation of the immune response When an invader attacks...  An antigen is phagocytized by the B cell  is broken into non-infective pieces  & attached to the cell’s MHC when processed through the cell’s machinery  MHC-antigen complex is placed on the cell membrane surface  where it is recognized by the T Helper cell. When help arrives...  The T-helper cell receptor with the B cell’s MHComplex  B cells proliferate... Antigen & T-helper cell Naïve cell Proliferation of cell line B cells differentiate into...  Antibody producing cells [attack mode]  Memory cells [remembers & future protection] Antigen & T-helper cell antibodies memory The RESULT...  The Antibody producing B cells mounts a successful attack against the Ag  the memory B cells save the “recognition ID” for many years in preparation for future invasion Pathology immune system Failure: immune deficiency - Hyperimmunity: - Hypersensitivity reactions -Autoimmunity -Transplant Rejection - Hypersensitivity Reactions 1. Type I Hypersensitivity 2. Type II Hypersensitivity 3. Type III Hypersensitivity 4. Type IV Hypersensitivity Hypersensitivity Reactions I (Immediate Hypersensitivity) II (Antibody Mediated Hypersensitivity) III (Immune-Complex Mediated Hypersensitivity) IV (Cell-Mediated Hypersensitivity) I II III Seconds to mints Immediate Mast cells Vasodilatation Eosinophils Asthma Hay fever Abs againt Antigens on cell surface or tissue components, or exogenous Mechanism of action: -Complement dependant: Direct lysis Opsonisation Example transfusion reactions HDNB AIHA Drug induced Deposition of immune complexes followed by accumulation of neutrophils. Ags: exogenous (bacteria,viruses) endogenous (DNA) -Clinical manifestations: i. Systemic (anaphylactic): itching, urticraia, erythema, respiratory difficulty, V&D, circulatory collapse. ii-Local: Skin: erythema Generalized (serum sickness) - Localized (Arthus reaction) A-Farmers lung B- acute poststreptococcal glomerulonephritis. C- SLE Where do they go? Kidney Blood Vessels Skin Joints Iv Mediated by specifically sensitized T cells. Delayed type hypersensitivity: By CD4 T cells Examples Allograft rejection - Contact dermatitis. - Autoimmunity. - Removal of tumor cells. T Y P E DESCRIPTIVE INI TIA TIO N NAME TIM E MECHANISM EXAMPLES Ag induces IgE bound to mast cells with release of vasoactive mediators Systemic anaphylaxis, Local anaphylaxis, Hay fever, Asthma, Eczema 58hrs Ab directed against cell-surface antigens Blood transfusion reactions, Haemolytic disease of the newborn, Autoimmune Haemolytic anaemia Arthus reaction (Localised); Systemic reactions disseminated rash, arthritis, glomerulonephritis Contact dermatitis, Tubercular lesions I IgE-mediated hypersensitivity 2-30 mins II Antibody-mediated cytotoxic hypersensitivity II I Immune-complex mediated hypersensitivity 28hrs Ag-Ab complexes deposited at various sites induces mast cell degranulation , PMN degranulation damages tissue I V cell-mediated hypersensitivity 2472hr s Memory TH1 cells release cytokines that recruit and activate macrophages Autoimmune diseases Immunity against self antigens Mechanisms: 1-Bypass of T cell a-Modification of antigen determinant sites. b-Cross reactions -Similar c- Polyclonal B cell activation: bypass the need for TH activation of Bcells Autoimmune diseases Immunity against self antigens 2-Abnormalitis in the regulation of the immune response: Loss of T suppressor function. 3-Release of Antigenes. 4- Genetic factors: Familial. Association with certain HLA types. 5- Role of viruses Autoimmune Disorders  Organ specific: Hashimoto’s thyroiditis, pernicious anaemia, vitiligo  Systemic: 1. Systemic lupus erythromatosis, 2. Rheumatoid arthritis, 3. Systemic sclerosis, 4. Poly arteritis nodosa, 5. vasculitis Immune deficiency disorders  Primary.  Secondary. Primary Immune Deficiency A) immunity:  Chronic granulomatous disease. phagocytosis pyogenic infections  Leukocyte adhesion defect.  Complement deficiency. B) Lymphocyte maturation defect: agammaglobulinaemia:, Severe combined immunodeficiency. C) T lymphocytes deficiency: congenital absence of thymus D) B lymphocytes deficiency:  Common variable immunodeficiency  Hyper IgM.  Selective Ab class deficiency. Secondary Immune Deficiency  Drugs.  Chronic debilitating infections.  Advanced malignancies.  Haematopoietic malignancies.  HIV infection. HIV Infection  Infects CD4 lymphocytes. Once inside, incorporates into cellular DNA. There, it either remains dormant or replicates (transcribed). Then particles bud out of surface.