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White Blood Cells and Immunity Prof. K. Sivapalan.

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Presentation on theme: "White Blood Cells and Immunity Prof. K. Sivapalan."— Presentation transcript:

1 White Blood Cells and Immunity Prof. K. Sivapalan

2 June 2013White Cells2 WHITE BLOOD CELLS. Colorless. Seen clearly only after staining. Blood count is 4,000 – 11,000 / mm 3. Important for the defense of the body. Life span of different cells vary. Classification: –Granulocytes and Agranulocytes on the basis of property of the cytoplasm. –polymophonuclear leucocytes and mononuclear leucocytes on the basis of the structure of the nucleus.

3 June 2013White Cells3 Neutrophil 50 – 70 % of the white cells in blood lobed nucleus. Fine granules in the cytoplasm [acidic and basic] – lysosomes. First line of defense against bacteria. Amoeboid movement and Phagocytosis (maximum 15 bacteria). “Pus cells” Half life is 6 hours and Production is about 100,000,000,000 / day.

4 June 2013White Cells4 Eosinophil Less than 5 % of white cells in blood. Bilobed nucleus, larger granules. Granules take acidic dye, and are anti histaminic. Mildly amoeboid. Attack parasites. Also found in GIT, respiratory, and urinary mucosa. Blood count is increased in allergic conditions.

5 June 2013White Cells5 Basophil. Less than 1 % of the white cells in blood. Nucleus is poorly differentiated three lobes, seen as Kidney shaped. Largest granules, take basic dye and contain histamine and heparine Responsible for anaphylactic type of Hypersensitivity.

6 June 2013White Cells6 Lymphocyte. About % of the white cells in blood % in babies. Most are found in the lymphatic tissues. Large and small cells seen Large single nucleus. Rim of clear cytoplasm. Responsible for adaptive immunity.

7 June 2013White Cells7 Monocyte. Less than 10 % of the white cells. Kidney shaped single nucleus. Abundant clear cytoplasm. Phagocytic and shows amoeboid movement. Becomes Macropharge in tissues.

8 June 2013White Cells8 Macropharge system. Kupffer cells in liver. Osteoclasts in bone. Alveolar cells in lungs. Microglia in brain. Histeocytes in tissues.

9 June 2013White Cells9 Defense reactions Immunity: –Ability to resist disease by foreign agents. Innate immunity: –Indiscriminate, first line. Acquired [adaptive] immunity: –Specific, powerful, delayed.

10 June 2013White Cells10 Innate immunity. Physical: –Skin, cilia + mucus, acid and tears. Biochemical: –Lyzozyme, sebaceous secretion, commensals in gut and vagina. Phagocytes: –Neutrophil, Monocyte, Macrophage. –Natural Killer cells [lymphocytes]. Pathological: –Inflammation. –Acute phase proteins.

11 June 2013White Cells11 Physical protection. Skin. Cilia and mucus. Acid in stomach. Flow of tears.

12 June 2013White Cells12 Phagocytosis.

13 June 2013White Cells13 Properties of phagocytes. Chemotaxis: –Chemical attraction by bacterial toxins, polysacharides, complements, antigen- antibody complexes. Amoeboid movement - psudopodia [actin + myosin] Leave capillaries through the pores- Diapedisis. Phagocytosis – some times need opsonization. Enzymatic digestion. [lysosomes- digestive enzymes, peroxidase(H 2 O 2 ), Myeloperoxidase (ClO - )

14 June 2013White Cells14 Opsonization. When antigens are harmful to phagocytes, the active site is covered by, Compliments or Antibodies to facilitate phagocytosis.

15 June 2013White Cells15 Recognition by phagocytes. Binding to receptors- polysaccharides or similar bacterial cell wall substances [nonspecific]. Electrical charge of the surface- positive charge in living tissue. No charge in dead tissues and negative out side of bacteria. Opsonized material is said to be “tasty” to phagocytes.

16 June 2013White Cells16 Inflammation. Products of tissue damage, some bacterial toxins and antigen – antibody complexes initiate inflammatory response. Vasodilatation and increased capillary permeability are important events. They facilitate entry of phagocytes and fibrin network to arrest spread of invading organisms. Cardinal signs: Redness Swelling Warmness Pain Loss of function.

17 June 2013White Cells17 Acquired [adaptive] immunity. Antigen: –A substance that can stimulate the immune mechanism. [antigenic – MW > Antibody: –Substance that is produced in response to antigen and reacts with it.

18 June 2013White Cells18 Antibody. Light and heavy chains. Variable portion – antigen binding. Constant -1 Hinge. Constant 2- complement binding. Constant 3- membrane binding.

19 June 2013White Cells19 Antibody types in blood. Monomer IgG Dimer IgA

20 June 2013White Cells20 Antibody types in blood. Pentamer IgM Membrane bound IgE

21 June 2013White Cells21 Humeral antibodies. IgG – 70 % [in serum- monomer] IgM – 10 % [confined to blood- pentamer] IgA – 15 % [blood- monomer, secretions- dimer] IgD - < 1 %.[ lot in membranes of B Lymphocytes]. IgE - Trace in blood [bound to mast cells]

22 June 2013White Cells22 Reactions of antibodies. 1.Direct action. -Agglutination. [IgM] -Precipitation. -Neutralization. -Lysis. 2.Activation of complement system. 3.Activation of anaphylactic system. 4.Chemo taxis.

23 June 2013White Cells23 Reaction of Complement System. 1.Activation of complement system.[C H 2] after antigen binding. 2.Lysis. 3.Opsonization. 4.Chemotaxis. 5.Agglutination. 6.Neutralization. 7.Inflamatory effects. 1.1.Compliments: -C1q, C1r, C1s, C4, C2, C3, C5, C6, C7, C8, C Activation: Ag/Ab complexes [C H 2] → clasical pathway. Bacteria [sugar] → alternative pathway.

24 June 2013White Cells24 Reaction of Anaphylactic System. Basophils and mastcells are activated by reaction of IgE attached to the membrane and release contents of the granules. Histamine: Local vasodialatation, ↑ capillary permiability. Slow reacting substance of anaphylaxis: prolong action- contraction of smooth muscles in broncheols. {protective → dangerous}

25 June 2013White Cells25 Cellular immunity. Antibody in the membrane of the lymphocyte. The cell is activated when antigen binds to the antibody.

26 June 2013White Cells26 Mechanism of Cellular Immunity. Cytotoxic T cell. Attaches to bacteria, virus infected cell, cancer cell or transplanted cells.  Effective against viral, fungal and some bacterial [tuberculosis] infections and cancer.  Responsible for tissue rejections in transplantation.

27 June 2013White Cells27 Lymphatic system. Thymus Spleen

28 June 2013White Cells28 Development of the immune system. Lymphocyte precursors. [Bone marrow] T lymphocytes. [Thymus ] B lymphocytes. [Bursa fabrecious, liver, bone marrow] Cytotoxic T cells[CD8] Plasma cells. Humeral immunity. Cellular immunity. Helper T cells [CD4] Memory cells. Processing Suppressor T cells

29 June 2013White Cells29 Diversity of immune system. Types of light chain- 2, heavy chain- 8. Variable portion:- –Random recombination of DNA in the gene. –10 8 – different molecules possible [B]. –10 15 T cell receptors possible. Recognition of self: –Clonal deletion. –Clonal anergy [prolonged hyporesponsive state]. –Suppressor T cells.

30 June 2013White Cells30 Activation of the immune system. Cytotoxic T cells and B cells lie in the lymphatic tissue after processing. When antigen enters the body ‘antigen presenting cells’ take the antigen. [dentritic cells and macropharges] They process the antigen, expose on the surface [incorporated in the cell membrane] and find the T of B cell for the antigen. The lymphocyte then proliferates and becomes a “clone” Some go dormant [memory cells] for activation next time. Others start secreting appropriate antibody [humeral immunity] or go out and attack [cellular immunity]

31 June 2013White Cells31 Activation of immune system. First exposure of antigen: –Delay of about 2 weeks. Second exposure: [more memory cells] –Quick response. –Potent response. –Long lasting.

32 June 2013White Cells32 Immunization. Active: –Introduce deactivated toxin and provoke immune response. Passive: –Introduce antobody for immediate need.

33 June 2013White Cells33 Hypersensitivity. Type I: –Allergy- IgE. Asthma, eczema, hay fever, urticaria, anaphylaxis. Type II: –Against antigens on the surface of cells or tissues:- transfusion reactions, acute glomerular nephritis, rheumatic fever. Type III: –Reaction of serum antibodies and excessive complexes formation. Type IV: –Cell mediated: contact dermatitis.

34 June 2013White Cells34 Immunodeficency syndromes. [Heriditary] Pluripotent stem cell. Lymphoid progenitor. Pre- B cell In bone marrow. Immature T cell. In thymus. B - cell IgM IgA IgG Ige CD8 cell CD4 Cell

35 June 2013White Cells35 Acquired immunodeficiency syndrome. Caused by HIV [human immunodeficiency virus] Binds to CD4 and reduces helper T cells. Results in failure of proliferation of CD8 cells and B cells. Eventually loss of immune function.

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