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Immunity

Immunity. Immunity is the capability of the body to fight against pathogenic microbes in order to prevent us from infectious diseases . There are basically two types of immunity: 1) Innate immunity 2) Adaptive immunity. Innate immune system

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Immunity

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  1. Immunity • Immunity is the capability of the body to fight against pathogenic microbes in order to prevent us from infectious diseases. • There are basically two types of immunity: 1) Innate immunity 2) Adaptive immunity

  2. Innate immune system • This is basically a natural immunity of an individual, also called as non-specific immune system or (in-born immunity(. • It includes all the mechanisms that protect the host from pathogenic microbes. • It provide prompt defense against infection but does not create any memory against a particular pathogen for future encountered

  3. Cells of Innate immuno system • White blood cells are main source to induce innate immunity. These cells are also known as leukocytes.. These leukocytes cells include: • NK cells are the basic part of innate immunity . These cells are called natural killer because they do not require any activation. They kill the microbes as soon as they produced inside the body [ • Eosinophils is low as compare to neutrophils and basophils. • Basophils play an important role in immunity. Due to activation of these cells histamine-releasing basophils are produced. They also take part in allergic reactions. [ • Mast cells:These cells are linked with allergic reactions along with chemokine. • Neutrophils are also called as granulocytes due to the existence of granules in their cytoplasm. These granules consists a mixture of toxic substances that hinders the growth of microbes

  4. Cells of Innate immuno system • Macrophage. These are the most efficient phagocytes and can phagocytize large number of bacteria or microbes. of infection . • Cytokines Operate only with that type of cells which having specific receptors on their surface. • Dendritic cells .

  5. Cells of adaptive immunityDifference between T cells and B cells • T cells and B cells are both generated in the bone marrow from stem cells or more precisely form the lymphoid common progenitor. • T cells or thymocytes maturate in the thymus, a lymphoid organ situated in the chest, while B cells mature in the bone marrow, at the same site of their generation. • Both T cells and B cells migrate to the bloodstream after their maturation and circulate between the peripheral lymphoid organs in an inactive state.

  6. Cells of adaptive immunityDifference between T cells and B cells • There are two types of activated T cells: Cytotoxic T cells responsible of the destruction of cells infected by intracellular pathogens, and helper T cells responsible of activating cytotoxic T cells, macrophages, and B cells. • B cells, on the other side, differentiate upon activation by helper T cells into one cell type, plasma cells capable of secreting antigen-specific antibodies. • Activated T cells present antigen receptors on their membrane and are not capable of secreting antibodies, whereas activated B cells are responsible for antibody secretion.

  7. Difference between Innate and Adaptive Immunity • Innate ImmunityAdaptive immunity • is already present in the body. in response to exposure to foreign substance. • Non-Specific Specific • Rapid Response Slow (1-2weeks) • Potency Limited and Lower potency High potency • Time span Once activated against The span of developed a specific type of antigen, the immunity can be lifelong or short remains throughout the lif • .Inheritance Innate type of immunity is cannot be inherited generally inherited from parents and passed to offspring.

  8. Difference between Innate and Adaptive Immunity .1 • .Allergic Reaction None Immediate and Delay hypersensitivity • 11.Used AgainstFor microbes Microbes and non-microbial substances called antigen • .MemoryNo memory long term memory • .Complement system activation Alternative and lectin pathways Classical pathway • .Anatomic and physiological barriers Skin, Mucous membranes, lymph node, spleen • Temp, pH, chemicals, etc., mucosal associated lymphoid tissue. • .Composition The innate immune system is composed of physical and chemical barriers, phagocytic composed of B cells and T cells leukocytes, dendritic cells, natural killer cells, and plasma proteins.1 .

  9. Antibodies immunoglobulins • IgG is the most predominant antibody found in the body and constitutes for 80% of the total antibody content in theserum. • It is the only antibody with the ability to cross the placental membrane and provide immunity to the fetus.

  10. Antibodies immunoglobulins • IgA is found in the mucous membranes of the gastrointestinal and respiratory tracts. It is located in mucus secretions, saliva, tears, and the colostrum. • It constitutes 13% of total antibody content found in the serumThe IgA1 antibody is the most prevalent and is also called secretory immunoglobulin

  11. Antibodies immunoglobulins • IgM is the largest antibody found in the body and is the first to be produced after an antigen enters the body. • It is found in the blood and the lymph fluid. It constitutes 6% of the total antibody content of the serum.

  12. Antibodies immunoglobulins • IgE antibody is also known as the reaginic antibody and is involved in hypersensitivity reactions or allergic responses. • It is found in the linings of the respiratory and intestinal tracts. • It is the least abundant antibody which constitutes about 0. 002% of the antibody content in serum. • The antigenic site binds to mast cells or basophils that are known to be involved in hypersensitivity reactions.

  13. Antibodies immunoglobulins • IgD antibody makes up less than 1% of the total antibody content of serum. • Its specific function is still unknown. However, it is thought to be involved in the process of B cell activation.

  14. HYPERSENSITIVITYREACTIONS • I (Immediate Hypersensitivity) • IIAntibody Mediated Hypersensitivity • III (Immune-Complex Mediated Hypersensitivity) • IV (Cell-Mediated Hypersensitivity

  15. Type I IMMEDIATE HYPERSENSITIVITY “Immediate” means seconds to minutes “Immediate Allergic Reactions”, which may lead to anaphylaxis, shock, edema, dyspnea death 1) Allergen exposure 2) IMMEDIATE phase: MAST cell degranulation, vasodilatation, vascular leakage, smooth muscle (broncho)-spasm

  16. Type of hypersensitivityImmuno Mechanism Immediate (type I) hypersensitivityAnaphylaxis; allergies bronchial asthma (atopic forms) Production of IgE antibodyÕimmediate release of vasoactiveamines and other mediators from mast cells; recruitment of inflammatory cells (late-phase reaction)Vascular dilation, edema, smooth muscle contraction, mucus production, inflammation Antibody-mediated (type II) hypersensitivity Autoimmune hemolytic a nemia; Production of IgG, IgMÕbinds to antigen on target cell Goodpasturesyndrome or tissueÕphagocytosis or lysis of target cell by activated complement or Fcreceptors recruitment of leukocytesCell lysis

  17. Type of hypersensitivity Immuno Mechanism Immune complex-mediated (type III) hypersensitivity Systemic lupus erythematosus; Arthus Reaction Deposition of antigen-antibody complexesÕcomplement activationÕ some forms ofglomerulonephritis recruitment of leukocytes by serum sickness; Arthus complement products and Fcreceptors ; Õrelease of enzymes Cell-mediated (type IV) hypersensitivity Contact dermatitis; tuberculosis Activated Tlymphocytes multiple sclerosis Õi) release of cytokines type I, diabetes macrophageactivation; ii) transplant rejection T cell-mediated cytotoxicity

  18. 3) LATE phase (hours, days): Eosinophils, PMNs, T-Cells, as expected with acute inflammation

  19. TYPE II DISEASES Autoimmune Hemolytic Anemia, AHA Idiopathic Thrombocytopenic Purpura, ITP Goodpasture Syndrome (Nephritis and Lung hemorrhage) Rheumatic Fever Myasthenia Gravis Graves Disease Pernicious Anemia, PA

  20. TYPE III HYPERSENSITIVITYIMMUNE COMPLEX MEDIATED • Antigen/Antibody “Complexes” (circulating) • Where do they go? • Kidney (Glomerular Basement Membrane) • Blood Vessels • Skin • Joints (synovium)

  21. TYPE III HYPERSENSITIVITYIMMUNE COMPLEX MEDIATED Common Type III Diseases • SLE (Lupus) • Poly(Peri)arteritis nodosa, Poststreptococcal glomerulonephritis • Arthus reaction (hrs) • Serum sickness (days) • (SYSTEMIC? Autoimmune

  22. TYPE IV HYPERSENSITIVITYCELL-MEDIATED (T-CELL)DELAYED HYPERSENSITIVITY • Tuberculin Skin Reaction • DIRECT ANTIGENCELL CONTACT • GRANULOMA FORMATION • CONTACT DERMATITIS

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