1. A DAPTIVE I MMUNITY Paula Ruedebusch, ARNP, DNP

2. 2 A DAPTIVE I MMUNITY Purposes: Destruction of infectious microorganisms that are resistant to inflammation Long-term highly effective protection against future exposure to the same microorganism Inducible Specific End products Immunoglobulins Lymphocytes (T cells, B cells)

3. 3 A DAPTIVE I MMUNITY ( CONT ’ D ) Components: Humoral—immunoglobulins (antibodies) Bind to antigens on bacteria and viruses Cellular—T cells Subpopulations (effector T cells) Kill target directly Stimulate other leukocytes Both produce memory cells Interact

4. 4 A DAPTIVE I MMUNITY ( CONT ’ D ) Active immunity Exposure to antigen Immunization Passive immunity Preformed antibodies or T cells are administered Maternal-fetal transmission Temporary

5. 5 Active Immunity (vaccination) Passive Immunity (antitoxins) Develops due to infection or immunization Preformed antibodies are injected There is a short lag period. Does not give immediate protection No lag period. Gives immediate protection. Effective immunity – it is long- lasting. Immunity is short-lived. Antibodies are quickly eliminated. Repeated doses give more and more protection (booster response) Repeated doses give less and less protection. Not useful in a person with immunodeficiency Useful to protect immunodeficient people

6. 6

7. 7

8. 8 A DAPTIVE I MMUNITY ( CONT ’ D ) Antigens Bind with antibodies, receptors on T and B cells Not necessarily immunogens Immunogens Induce production of antibodies, T and B cells Depends on foreignness, molecular size, quantity All are antigens Entry route (intravenous, intradermal, oral) stimulates different lymphoid tissue Genetics Other factors (nutrition, concurrent disease, drugs)

9. 9 V ACCINE R OUTES

10. 10 A NTIGENS Antigenic determinant (epitope) = ON antigen Antigenic binding site (paratope) = ON antibody Self-antigen Molecular size Haptens Allergens

11. 11 H UMORAL I MMUNITY Immunoglobulins (antibodies) Produced by plasma cells Types: IgG IgA IgM IgD IgE

12. 12 A NTIBODIES Also called immunoglobulins Produced by plasma cells Classes of antibody IgG, IgA, IgM, IgE, and IgD Characterized by antigenic, structural, and functional differences

13. 13 A NTIBODIES ( CONT ’ D )

14. 14

15. 15 A NTIBODY S TRUCTURE Antigen-binding fragment (Fab) Recognition sites (receptors) for antigenic determinants Crystalline fragment (Fc) Responsible for biologic function Polypeptide chains (4) Light chains (2) and heavy chains (2)

16. 16 H UMORAL I MMUNITY Antigen-Antibody Binding: Antigenic determinant (epitope) = area of molecule that is recognized by the antibody Antigen-binding site (paratope) = the matching portion on the antibody

17. 17 A NTIBODY F UNCTIONS Antibody functions: Direct Neutralization Agglutination Precipitation Indirect Inflammation Phagocytosis Complement Degree of antibody protection is assessed by an antibody titer

18. 18 D IRECT AND I NDIRECT F UNCTIONS OF A NTIBODIES

19. 19 T ITER EXAMPLE

20. 20 I MMUNOLOGIC M ECHANISMS OF I NFLAMMATION

21. 21 I MMUNOGLOBULIN A (I G A) ( CONT ’ D ) IgAs found in body secretions are dimers anchored by a J chain and a “secretory” piece Secretory piece may function to protect IgAs against enzyme degradation

22. 22 I MMUNOGLOBULIN D (I G D) Limited information on IgD function Low concentration in the blood Located primarily on the surface of developing B lymphocytes Function as one type of B cell antigen receptor

23. 23 I MMUNOGLOBULIN E (I G E) Least concentrated of the immunoglobulin classes in the circulation Mediator of many common allergic responses Defender against parasites

24. 24 I G E F UNCTION Provides protection from large parasites Initiates an inflammatory reaction to attract eosinophils When produced against innocuous environmental antigens, they are a common cause of allergies

25. 25 I G E F UNCTION ( CONT ’ D )

26. 26 I MMUNOGLOBULIN G (I G G) Most abundant class (80%-85%) Accounts for most of the protective activity against infections Transported across the placenta Four classes: IgG1 IgG2 IgG3 IgG4

27. 27 I MMUNOGLOBULIN M (I G M) Largest of the immunoglobulins First antibody produced during the primary response to an antigen Synthesized during fetal life

28. 28 S ECRETORY (M UCOSAL ) I MMUNE S YSTEM Lymphoid tissues that protect the external surfaces of the body Antibodies present in tears, sweat, saliva, mucus, and breast milk IgA is the dominant immunoglobulin Small numbers of IgG and IgM are present

29. 29 S ECRETORY (M UCOSAL ) I MMUNE S YSTEM ( CONT ’ D )

30. 30 C ELLULAR I MMUNITY T lymphocytes: T Cytotoxic (Tc) cells T Helper (Th) cells Memory cells

31. 31 A DAPTIVE I MMUNITY Clonal diversity Production of T and B lymphocytes Antigen recognition Lymphocyte specificity Clonal selection Antigen processing and presentation Complex cellular interactions

32. 32 G ENERATION OF C LONAL D IVERSITY All necessary receptor specificities are produced Takes place in the primary (central) lymphoid organs (thymus, bone marrow) Results in immature but immunocompetent T and B cells Primarily occurs in the fetus

33. 33 C LONAL D IVERSITY B Cell Development: Production, proliferation, differentiation in bone marrow Travel to lymphoid tissue and reside there as immunocompetent cells Each cell responds to only one specific antigen T Cell Development: The thymus is the central lymphoid organ of T cell development Development of antigen-specific T cell receptors (TCRs) Leave thymus, travel to and reside in lymphoid tissue as mature immunocompetent cells

34. 34 C LONAL S ELECTION : A NTIGEN P ROCESSING AND P RESENTATION Initiated when T and B cells interact with an antigen Must first be processed and then presented by antigen-processing (antigen-presenting) cells (APCs) Results: Differentiation of B cells into active antibody-producing cells (plasma cells) Differentiation of T cells into effector cells, such as T- cytotoxic cells

35. 35 C LONAL S ELECTION : A NTIGEN P ROCESSING AND P RESENTATION ( CONT ’ D ) For processing and presentation to occur, the antigen must be of the appropriate type, the lymphocytes must be prepared to recognize the presented antigen, and the antigen must be presented appropriately https://www.youtube.com/watch?v=bfL6ORCVuF4

36. 36 A NTIGEN P ROCESSING AND P RESENTATION ( CONT ’ D )

37. 37 A NTIGEN P RESENTATION Major histocompatibility complex (MHC) Glycoproteins on the surface of all human cells (except RBCs) Also referred to as human leukocyte antigens (HLAs) Dendritic cells – antigen presenting leukocyte found in mucosa and lymphoid tissues that initiate a primary immune response.

38. 38 P RIMARY AND S ECONDARY R ESPONSES Primary response Initial exposure Latent period or lag phase B cell differentiation is occurring After 5 to 7 days, an IgM antibody for a specific antigen is detected An IgG response equal or slightly less follows the IgM response

39. 39 P RIMARY AND S ECONDARY R ESPONSES ( CONT ’ D ) Secondary response More rapid Larger amounts of antibody are produced Rapidity is caused by the presence of memory cells that do not have to differentiate IgM is produced in similar quantities to the primary response, but IgG is produced in considerably greater numbers

40. 40 S UPERANTIGENS (SAG S ) Activates a large population of T-lymphocytes regardless of antigen specificity SAGs induce an excessive production of cytokines Causes fever, low blood pressure, and potentially shock

41. 41 P EDIATRIC I MMUNITY Fetus has sufficient IgM but deficient IgG, IgA responses Maternal antibodies provide protection within the fetal circulation and during the first months of life Immunologically immature when born with deficiencies in antibody production, phagocytic activity, and complement activity

42. 42 F ETAL AND N EONATAL I MMUNITY

43. 43 A GING AND I MMUNE F UNCTION Decreased T cell activity Thymic size is 15% of its maximum size Thymic hormone production drops, as does the organ's ability to mediate T cell differentiation Decreased antibody response to antigens Increase in circulating antigen-antibody complexes Increase in circulating autoantibodies Decrease in circulating memory B cells

44. 44 T EST Y OURSELF ! Which of the following terms describes the type of immunity that occurs when preformed antibodies transfer from donor to recipient? A. Active B.Passive C.Cellular D. Memory

45. 45 C LINICAL APPLICATION #1 Mr. Jones became infected with the HIV virus on Friday night. The following Monday, he donated a unit of blood. The blood will be screened for the presence of HIV using an antibody test. Will his blood test be positive for the virus? Why?

46. 46 C LINICAL A PPLICATION #2 Judi Smith, age 5, is about to receive a vaccine during her regular checkup. Her mother asks you why she needs this “shot.”