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Immune Response to Infection

Immune Response to Infection. CLS 212 – Medical Microbiology Mrs. Amany Ahmed Niazy. Immunity. How our bodies fight pathogens in an attempt to prevent the infectious diseases that they cause. . Immune Response to Infection. It has two major components: Innate (non-specific) immunity.

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Immune Response to Infection

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  1. Immune Response to Infection CLS 212 – Medical Microbiology Mrs. Amany Ahmed Niazy

  2. Immunity • How our bodies fight pathogens in an attempt to prevent the infectious diseases that they cause.

  3. Immune Response to Infection • It has two major components: • Innate (non-specific) immunity. • Adaptive (specific) immunity.

  4. Immune Response to Infection • Innate (non-specific) immunity: • Natural resistance, people are borne with it. • It includes the role of  • Physical barrier (eg. Skin & mucus membranes). • Cellular system (eg. phygocytic cells). • Chemical system (circulating glycoproteins such as complement) • Inflammation. • Fever • Adaptive (specific) immunity: • It has the ability to develop new responses that are highly specific to molecular components of infectious agent called antigen (Ag) • Cellular response • Humeral response (Antibody production Ab)

  5. Innate (Nonspecific) Immunity • Physical Barriers: • The thick layer of skin is a very strong barrier. • The presence of insoluble keratin on skin and the high salt concentration. • Mucosal membranes are not as tough as skin but are bathed in secretions that can destroy microorganism such as: • lysozyme destroy peptidoglycan of bacterial cell wall • Also the presence of cilia in respiratory tract that trap and move cells away from the alveoli.

  6. Innate (Nonspecific) Immunity • Cellular Response:

  7. Innate (Nonspecific) Immunity • Cellular Response: • All these cells came from stem cells in the bone marrow. • In general they are called leukocytes (include neutrophills,macrophages, eosinophils…etc) • They are found through out the body either in circulation or in specific tissue, and they are highly concentrated in lymph nodes. • They include phagocytes which are cells that specialize in engulphing and digesting microbes and cell debris. • Thymus spleen, and lymph nodes are considered the immune system.

  8. Innate (Nonspecific) Immunity • Cellular Response: • Eg. Macrophages: • Found in circulation or tissue • Have surface receptor that recognize and bind (non-specifically) to components commonly found on pathogens. • They do phagocytosis and digestion.

  9. Innate (Nonspecific) Immunity

  10. Innate (Nonspecific) Immunity • Cellular Response: • Eg. Dendritic Cells: • They have distinctive star-like morphology. • Found in tissue (skin and mucus membranes) • They migrate to lymph nod and spleen. • Phagocytosis and digestion

  11. Innate (Nonspecific) Immunity • Other cells • Neutrophils in circulation pahgocytosis and digestion. • Eosinophils immunity to parasites. • Basophils  release histamine which is responsible to hypersensitivity reactions.

  12. Innate (Nonspecific) Immunity • Chemical Mediators: • Cytokines: • Cytokines - a large family of proteins that mediate and regulate the IMMUNE RESPONSE. • Leukocytes (white BLOOD cells) produce cytokines. • There are more than 100 cytokines, which may act independently or synergistically with other cytokines

  13. Innate (Nonspecific) Immunity • Chemical Mediators: • Cytokines: • Among the action of cytokines is: • prompt cells to migrate to specific locations in the body. • stimulation of the numerous molecules that participate in the immune response. • Cytokines may act on: • Cells that produce them. • Cells in proximity to them. • Cells throughout the body.

  14. Innate (Nonspecific) Immunity • Chemical Mediators: • Complement system: • Consist of 30 different blood proteins. . • They are found in inactive form in theplasmaof healthy individuals. • Once triggered the components of complement system are activated in a fixed sequence (step-wise manner). • This can affect the pathogen in different ways, like: • enhancing phagocytosis • Activation of leukocytes • Lysis of bacterial cell walls.

  15. Innate (Nonspecific) Immunity • Inflammation: • When invading microorganisms or tissue damage is detected inflammation occur. • It include; redness, heat, edema, and pain. • During inflammation, cells lining the blood vessels in the affected aria become more permeable; allowing proteins (such as complement) and cells (such as phagocytes) to leak into the affected tissue. • The purpose of inflammation is to localize an infection, neutralize toxins, and aid in the repair of damaged tissues.

  16. Innate (Nonspecific) Immunity • Fever: • Elevated body temperatures can slow down or kill some fastidious pathogens. • It stimulate leukocytes to destroy pathogens. • Stimulate the production of certain chemical mediators.

  17. Adaptive (Specific) Immunity • It is extraordinarily complex system. • It involves lymphocytes (B-cells and T-cells) • It is highly specific. • It has memory function(accelerated response when pathogen return). • It function in two broad arms: • Humoral response. • Cellular response.

  18. Some Definitions • Antigens (Ag): • any agent that can stimulate the production of antibodies (Ab). • It can be microorganisms, molecule, protein …etc. • Antibodies (Ab): • Specific glycoproteins produced by lymphocytes (B-cells) in response to the presence of an Ag. Each Ab is specific to the Ag that stimulates its production

  19. Adaptive (Specific) Immunity • Humoral Immunity: • Involve B-cell and Antibody (Ab) production. • B-cells come from bone marrow. • Foreign Ag enter human host  bind to Ab on B-cells surface  B-cell multiply, and produce more Ab’s with the same specificity. • Eventually their will be enough Ab to bind more of the antigen.

  20. Adaptive (Specific) Immunity Ab’s are unable to enter cells, including cell containing intracellular pathogens. Fortunately, there is a part of the immune system capable of controlling infections caused by intracellular pathogens. Cellular Response (=Cell Mediated Immunity)

  21. Adaptive (Specific) Immunity • Cellular response. • It is mediated through T-cells. • T-cells come from bone marrow and mature in thymus. • It respond to Ag by: • Directly attacking and killing foreign cells or infected host cells. • Or by secreting cytokines to activate other cells.

  22. Immunity Innate (nonspecific) Immunity Adaptive (specific) Immunity Physical Barrier Cellular Response Humoral Response Inflamation Chemical System Cellular System

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