<ul><li>Introduction to Immunology </li></ul><ul><li>Dr. Catherine Gerald Mkindi </li></ul><ul><li>MVM, BVM, SUA </li></ul>
What is immunology? <ul><li>Immune (Latin- “immunus”) </li></ul><ul><ul><li>To be free, exempt </li></ul></ul><ul><ul><li>...
Immune response <ul><li>The immune response is the host reaction to infection/invasion. </li></ul><ul><li>The body is unde...
Types of Immunity <ul><li>Innate Immunity </li></ul><ul><ul><li>Host defense mechanisms that act from the start of an infe...
Types of Immunity <ul><li>Humoral immunity </li></ul><ul><ul><li>Immunity that is mediated by antibodies </li></ul></ul><u...
Humoral and cellular immunity   (antibody mediated or cellular)
Immune System Innate /Nonspecific Adaptive /Specific/ Acquired Protects/re-exposure Cellular Components Humoral Components...
Development of the Immune System <ul><li>Many cells of the immune system derived from the bone marrow </li></ul><ul><li>He...
Cells of the immune system
Lymphocytes <ul><li>Important in both </li></ul><ul><li>humoral and cell </li></ul><ul><li>mediated immunity </li></ul><ul...
<ul><li>Natural Killer cells </li></ul><ul><ul><li>Kills cells infected with certain viruses </li></ul></ul><ul><ul><li>Bo...
Monocytes/Macrophage <ul><li>Phagocytosis and killing of microorganisms </li></ul><ul><ul><li>Activation of T cells and in...
Dendritic Cells <ul><li>Activation of T cells and initiate adaptive immunity </li></ul><ul><li>Found mainly in lymphoid ti...
Mast Cells <ul><li>Expulsion of parasites through release of granules </li></ul><ul><li>Histamine, leukotrienes, chemokine...
Neutrophil <ul><li>Granulocyte </li></ul><ul><ul><li>Cytoplasmic granules </li></ul></ul><ul><li>Polymorphonuclear </li></...
Eosinophils <ul><li>Kills Ab-coated parasites through degranulation </li></ul><ul><li>Involved in allergic inflammation </...
Lymphoid organs
Function of the Immune System (Self/Non-self Discrimination <ul><li>To protect from pathogens </li></ul><ul><ul><li>Intrac...
Innate immune responses <ul><li>Anatomical barriers </li></ul><ul><ul><li>Mechanical factors </li></ul></ul><ul><ul><li>Ch...
Anatomical Barriers - Mechanical Factors Flushing action of tears, saliva, mucus, urine Epithelium ( e.g.  nasopharynx) Mu...
Anatomical Barriers - Chemical Factors Anatomical Barriers - Chemical Factors Opsonin Sufactants (lung) Antimicrobial Defe...
Anatomical Barriers - Biological Factors Antimicrobial substances Competition for nutrients and colonization Normal flora ...
Humoral Components Various effects Cytokines Breaks down bacterial cell walls Lysozyme Compete with bacteria for iron Lact...
Cellular Components Killing of certain parasites Eosinophils Killing of virus-infected and altered self targets NK and LAK...
Adaptive/ Acquired/ Specific Immunity
Key characteristics of the adaptive immune responses <ul><li>Specificity  </li></ul><ul><li>Adaptability  </li></ul><ul><l...
Types of Acquired Immunity <ul><li>I.  Naturally Acquired Immunity:  Obtained in the course of daily life. </li></ul><ul><...
Types of Acquired Immunity (Continued) <ul><li>II. Artificially Acquired Immunity:  Obtained by receiving a vaccine or imm...
Cells of adaptive immune responses
B lymphocytes Involved in  humoral  CD3 molecule  B-cell receptor (BCR, Ag recognition) T-lymphocytes  Function Surface co...
T-lymphocytes Involved in both humoral and cell-mediated responses CD3 molecule  T-cell receptor (TCR, Ag recognition) T-l...
T helper cells (CD 4+ cells) 1. Recognizes antigen presented within Class II MHC 2. Promotes differentiation of B-cells an...
Cytotoxic T cells (CD 8+ cells) Recognizes antigen presented within Class I MHC  Kills cells expressing appropriate antige...
T Suppressor Cells (CD 8+ cells) Downregulates the activities of other cells CD8 molecule Suppressor T-cells (TS) Function...
Macrophages Bind Fc portion of immunoglobulin (enhances phagocytosis)  Bind complement component C3b (enhances phagocytosi...
Dendritic Cells Antigen presentation within Class II MHC Class II MHC molecule Dendritic cells Function Surface components...
Primary and Secondary Immune Responses
<ul><li>The figure illustrates the production of antibody in response to antigenic substances. In this figure, an animal w...
Comparison   of Innate and Adaptive Immunity <ul><li>Innate Immunity: </li></ul><ul><li>Fast-acting  </li></ul><ul><li>Les...
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Blsy2 immunology 1

  1. 1. <ul><li>Introduction to Immunology </li></ul><ul><li>Dr. Catherine Gerald Mkindi </li></ul><ul><li>MVM, BVM, SUA </li></ul>
  2. 2. What is immunology? <ul><li>Immune (Latin- “immunus”) </li></ul><ul><ul><li>To be free, exempt </li></ul></ul><ul><ul><li>People survived ravages of epidemic diseases when faced with the same disease again </li></ul></ul><ul><li>The study of physiological mechanisms that humans and other animals use to defend their bodies from invading organisms </li></ul><ul><ul><li>Bacteria - Viruses </li></ul></ul><ul><ul><li>Fungi - Parasites - Toxins </li></ul></ul>
  3. 3. Immune response <ul><li>The immune response is the host reaction to infection/invasion. </li></ul><ul><li>The body is under constant attack by microorganisms in the environment. </li></ul><ul><li>pathogen : an infectious agent that causes disease </li></ul><ul><li>Infectious disease occurs when a microorganism succeeds in evading or overwhelming host defenses to establish a local site of infection and replication. In order for a pathogen to enter the body it must first overcome the innate immune response and the adaptive immune response . </li></ul>
  4. 4. Types of Immunity <ul><li>Innate Immunity </li></ul><ul><ul><li>Host defense mechanisms that act from the start of an infection but do not adapt to a particular pathogen </li></ul></ul><ul><ul><li>Recognize “patterns’ of a.a., saccharides, etc.. </li></ul></ul><ul><li>Adaptive Immunity </li></ul><ul><ul><li>Response of an antigen specific B and T lymphocytes to an antigen </li></ul></ul><ul><ul><li>Immunological memory </li></ul></ul>
  5. 5. Types of Immunity <ul><li>Humoral immunity </li></ul><ul><ul><li>Immunity that is mediated by antibodies </li></ul></ul><ul><ul><li>Can be transferred by to a non-immune recipient by serum </li></ul></ul><ul><li>Cell Mediated Immunity </li></ul><ul><ul><li>Immune response in which antigen specific T cells dominate </li></ul></ul>
  6. 6. Humoral and cellular immunity (antibody mediated or cellular)
  7. 7. Immune System Innate /Nonspecific Adaptive /Specific/ Acquired Protects/re-exposure Cellular Components Humoral Components Humoral Components Cellular Components
  8. 8. Development of the Immune System <ul><li>Many cells of the immune system derived from the bone marrow </li></ul><ul><li>Hematopoetic stem cell differentiation </li></ul>
  9. 9. Cells of the immune system
  10. 10. Lymphocytes <ul><li>Important in both </li></ul><ul><li>humoral and cell </li></ul><ul><li>mediated immunity </li></ul><ul><li>B-cells produce antibodies </li></ul><ul><li>T- cells </li></ul><ul><ul><ul><ul><li>Cytotoxic T cells </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Helper T cells </li></ul></ul></ul></ul><ul><li>Memory cells </li></ul>
  11. 11. <ul><li>Natural Killer cells </li></ul><ul><ul><li>Kills cells infected with certain viruses </li></ul></ul><ul><ul><li>Both innate and adaptive </li></ul></ul><ul><ul><li>Antigen presentation </li></ul></ul>
  12. 12. Monocytes/Macrophage <ul><li>Phagocytosis and killing of microorganisms </li></ul><ul><ul><li>Activation of T cells and initation of immune response </li></ul></ul><ul><li>Monocyte is a young macrophage in blood </li></ul><ul><li>There are tissue-specific macrophages </li></ul><ul><li>Antigen Presentation </li></ul>
  13. 13. Dendritic Cells <ul><li>Activation of T cells and initiate adaptive immunity </li></ul><ul><li>Found mainly in lymphoid tissue </li></ul><ul><li>Function as antigen presenting cells (APC) </li></ul><ul><li>Most potent stimulator of T-cell response </li></ul>
  14. 14. Mast Cells <ul><li>Expulsion of parasites through release of granules </li></ul><ul><li>Histamine, leukotrienes, chemokines, cytokines </li></ul><ul><li>Also involved in allergic responses </li></ul>
  15. 15. Neutrophil <ul><li>Granulocyte </li></ul><ul><ul><li>Cytoplasmic granules </li></ul></ul><ul><li>Polymorphonuclear </li></ul><ul><li>Phagocytosis </li></ul><ul><li>Short life span (hours) </li></ul><ul><li>Very important at “clearing” bacterial infections </li></ul><ul><li>Innate Immunity </li></ul><ul><li>CD 66 membrane marker </li></ul>
  16. 16. Eosinophils <ul><li>Kills Ab-coated parasites through degranulation </li></ul><ul><li>Involved in allergic inflammation </li></ul><ul><li>A granulocyte </li></ul><ul><li>Double Lobed nucleus </li></ul><ul><li>Orange granules contain toxic compounds </li></ul>
  17. 17. Lymphoid organs
  18. 18. Function of the Immune System (Self/Non-self Discrimination <ul><li>To protect from pathogens </li></ul><ul><ul><li>Intracellular ( e.g. viruses and some bacteria and parasites) </li></ul></ul><ul><ul><li>Extracellular ( e.g. most bacteria, fungi and parasites) </li></ul></ul><ul><li>To eliminate modified or altered self </li></ul>
  19. 19. Innate immune responses <ul><li>Anatomical barriers </li></ul><ul><ul><li>Mechanical factors </li></ul></ul><ul><ul><li>Chemical factors </li></ul></ul><ul><ul><li>Biological factors </li></ul></ul><ul><li>Humoral components </li></ul><ul><ul><li>Complement </li></ul></ul><ul><ul><li>Coagulation system </li></ul></ul><ul><ul><li>Cytokines </li></ul></ul><ul><li>Cellular components </li></ul><ul><ul><li>Neutrophils </li></ul></ul><ul><ul><li>Monocytes and macrophages </li></ul></ul><ul><ul><li>NK cells </li></ul></ul><ul><ul><li>Eosinophils </li></ul></ul>
  20. 20. Anatomical Barriers - Mechanical Factors Flushing action of tears, saliva, mucus, urine Epithelium ( e.g. nasopharynx) Mucociliary elevator Ciliated epithelium ( e.g. respiratory tract) Peristalsis Non-ciliated epithelium ( e.g. GI tract) Mucous Membranes Physical barrier Desquamation Squamous epithelium Skin Mechanism Cell type System or Organ
  21. 21. Anatomical Barriers - Chemical Factors Anatomical Barriers - Chemical Factors Opsonin Sufactants (lung) Antimicrobial Defensins (respiratory & GI tract) Low pH Lysozyme and phospholipase A HCl (parietal cells) Tears and saliva Mucous Membranes Anti-microbial fatty acids Sweat Skin Mechanism Component System or Organ
  22. 22. Anatomical Barriers - Biological Factors Antimicrobial substances Competition for nutrients and colonization Normal flora Skin and mucous membranes Mechanism Component System or Organ
  23. 23. Humoral Components Various effects Cytokines Breaks down bacterial cell walls Lysozyme Compete with bacteria for iron Lactoferrin and transferrin Increase vascular permeability Recruitment of phagocytic cells Β -lysin from platelets – a cationic detergent Coagulation system Lysis of bacteria and some viruses Opsonin Increase in vascular permeability Recruitment and activation of phagocytic cells Complement
  24. 24. Cellular Components Killing of certain parasites Eosinophils Killing of virus-infected and altered self targets NK and LAK cells Phagocytosis and intracellular killing Extracellular killing of infected or altered self targets Tissue repair Antigen presentation for specific immune response Macrophages Phagocytosis and intracellular killing Inflammation and tissue damage Neutrophils Functions Cell
  25. 25. Adaptive/ Acquired/ Specific Immunity
  26. 26. Key characteristics of the adaptive immune responses <ul><li>Specificity </li></ul><ul><li>Adaptability </li></ul><ul><li>Memory </li></ul>
  27. 27. Types of Acquired Immunity <ul><li>I. Naturally Acquired Immunity: Obtained in the course of daily life. </li></ul><ul><ul><li>A. Naturally Acquired Active Immunity: </li></ul></ul><ul><ul><li>Antigens or pathogens enter body naturally. </li></ul></ul><ul><ul><li>Body generates an immune response to antigens. </li></ul></ul><ul><ul><li>Immunity may be lifelong (chickenpox or mumps) or temporary (influenza or intestinal infections). </li></ul></ul><ul><ul><li>B. Naturally Acquired Passive Immunity: </li></ul></ul><ul><ul><li>Antibodies pass from mother to fetus via placenta or breast feeding (colostrum). </li></ul></ul><ul><ul><li>No immune response to antigens. </li></ul></ul><ul><ul><li>Immunity is usually short-lived (weeks to months). </li></ul></ul><ul><ul><li>Protection until child’s immune system develops. </li></ul></ul>
  28. 28. Types of Acquired Immunity (Continued) <ul><li>II. Artificially Acquired Immunity: Obtained by receiving a vaccine or immune serum. </li></ul><ul><ul><li>1. Artificially Acquired Active Immunity: </li></ul></ul><ul><ul><li>Antigens are introduced in vaccines (immunization). </li></ul></ul><ul><ul><li>Body generates an immune response to antigens. </li></ul></ul><ul><ul><li>Immunity can be lifelong (oral polio vaccine) or temporary (tetanus toxoid). </li></ul></ul><ul><ul><li>2. Artificially Acquired Passive Immunity: </li></ul></ul><ul><ul><li>Preformed antibodies (antiserum) are introduced into body by injection. </li></ul></ul><ul><ul><ul><li>Snake antivenom injection from horses or rabbits. </li></ul></ul></ul><ul><ul><li>Immunity is short lived (half life three weeks). </li></ul></ul><ul><ul><li>Host immune system does not respond to antigens. </li></ul></ul>
  29. 29. Cells of adaptive immune responses
  30. 30. B lymphocytes Involved in humoral CD3 molecule B-cell receptor (BCR, Ag recognition) T-lymphocytes Function Surface components Cell group
  31. 31. T-lymphocytes Involved in both humoral and cell-mediated responses CD3 molecule T-cell receptor (TCR, Ag recognition) T-lymphocytes Function Surface components Cell group
  32. 32. T helper cells (CD 4+ cells) 1. Recognizes antigen presented within Class II MHC 2. Promotes differentiation of B-cells and cytotoxic T-cells 3. Activates Macrophages CD4 molecule Helper T-cells (TH) Function Surface components Cell group
  33. 33. Cytotoxic T cells (CD 8+ cells) Recognizes antigen presented within Class I MHC Kills cells expressing appropriate antigen CD8 molecule Cytotoxic T-cells (CTL) Function Surface components Cell group
  34. 34. T Suppressor Cells (CD 8+ cells) Downregulates the activities of other cells CD8 molecule Suppressor T-cells (TS) Function Surface components Cell group
  35. 35. Macrophages Bind Fc portion of immunoglobulin (enhances phagocytosis) Bind complement component C3b (enhances phagocytosis) Antigen presentation within Class II MHC Secrete IL-1 (macrokine) promoting T-cell differentiation and proliferation Can be &quot;activated&quot; by T-cell lymphokines 1. Immunoglobulin Fc receptor 2. Complement component C3b receptor 3. Class II MHC molecule Macrophages Function Surface components Cell group
  36. 36. Dendritic Cells Antigen presentation within Class II MHC Class II MHC molecule Dendritic cells Function Surface components Cell group
  37. 37. Primary and Secondary Immune Responses
  38. 38. <ul><li>The figure illustrates the production of antibody in response to antigenic substances. In this figure, an animal was injected with Antigen A at day 0. Antigen A invokes a primary response beginning about day 4, as indicated by a rise in the specific antibody titer (titer = measure of the amount of antibody in the animal's serum per unit volume). Initially, this antibody is mostly IgM (and some IgG). After a peak titer between days 7 and 10, the response decreases rapidly. If the animal is then reinjected with Antigen A at day 28, the production of antibody begins almost immediately and reaches a level 1000-fold greater that that seen in the primary response. This is known as the secondary response and the principal antibody produced is IgG. If a second antigen (Antigen B) is also injected at the same time as the reinjection of Antigen A, however, only a primary response to Antigen B is observed. These results demonstrate that: </li></ul><ul><li>The immune response is specific. </li></ul><ul><li>The immune response has memory. </li></ul>
  39. 39. Comparison of Innate and Adaptive Immunity <ul><li>Innate Immunity: </li></ul><ul><li>Fast-acting </li></ul><ul><li>Less specific recognition </li></ul><ul><li>Early during evolution </li></ul><ul><li>e.g. phagocytes, barriers to infection such as skin and mucus surfaces </li></ul><ul><li>Adaptive Immunity: </li></ul><ul><li>Specificity </li></ul><ul><li>Distinguish antigens sometimes present from those always present </li></ul><ul><li>Memory and Recall </li></ul>

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