1. Disorders Associated with the Immune System

2. Disorders Associated with the Immune System
The Immune system does not always run perfectly
It may over respond - hypersensitivities
Hypersensitivities ~ allergy
4 types
I, II and III - are humoral
IV is cellular
It may react to your own cells - Autoimmune
Immune Deficiencies - unable to response to new pathogens

3. Hypersensitivity Reactions
Response to antigens (allergens) leading to damage
First exposure to antigen called “allergen” sensitized, second - over reaction
Skin testing
Desensitization can help improve reaction in about 70% of individuals.
Produce IgG to antigen (allergen) and hide it from Mast cells and IgE’s

4. Hypersensitivities
Type I — Anaphylaxis. Mast cells degranulate when IgE antibodies on surface bind to pathogens or allergens (antigens that invoke too strong a reaction)
Type II — Antibodies react with cell-surface antigens or cells you own or that have been put in you
Type III (Immune Complex) — IgM, IgG, complement immune complexes deposit in tissues
Type IV — Mediated by TD cells

5. Type I (Anaphylactic) Reactions
anaphylaxis - against protection
May be localized or systemic
Figure 19.3

6. Type I (Anaphylactic) Reactions
Involves IgE antibodies and Degranulation of Mast Cells
Histamine and mediators of anaphylatics
Localized: Hives or asthma from contact or inhaled antigens and allergies - dust mite feces, animal dander
hay fever upper respiratory
asthma lower respiratory
Systemic: Shock from ingested or injected antigens like drugs, insect venom,
Figure 19.1a

7. Mast Cells
Figure 19.1

8. Type II (Cytotoxic) Reactions
Involve IgG or IgM antibodies and complement
Cell bound Ag
Host cells with foreign antigen or drug acting as one
Complement activation causes cell lysis, inflammation or damage by macrophages
Transfusion reactions
Rh incompatibility
Autoimmunity examples:
Grave’s disease (thyroxin receptors)
Myasthenia Gravis (ACh receptors)

9. ABO Blood Group System
Table 19.2

10. Hemolytic Disease of the Newborn
Figure 19.4

11. Hemolytic Disease of the Newborn
RhoGAM Anti-Rh
Gamma globulin

12. Drug-induced Thrombocytopenic Purpura
Disseminating Intravascular Coagulation
DIC is a disorder of diffuse activation of the clotting cascade that results in depletion of clotting factors in the blood.
Figure 19.5

13. Type III (Immune Complex) Reactions
IgG, IgM and complement and antigens form complexes that lodge in basement membranes.
Small soluble complexes activate complement cascade
Glomerulonephritis, Lupus, rheumatoid arthritis
Figure 19.6

14. Type IV Cell mediated 1 - 2 day delay
T-cells attack tissue they shouldn’t
Rejection of transplanted tissues
Insulin - dependent diabetes mellitus
Skin test for Mycobacterium tuberculosis and M. leprae
Allergic dermatitis
Poison oak and ivy
Cosmetics, metals in jewelry
detergents

15. Type IV (Cell-Mediated) Reactions
Delayed-type hypersensitivities due to TD cells
Cytokines attract macrophages and initiate tissue damage
Figure 19.8

16. Autoimmune Diseases
Clonal deletion during fetal development ensures self-tolerance
Autoimmunity is loss of self-tolerance

17. Reactions Related to the Human Leukocyte Antigen (HLA) Complex
Histocompatibility antigens: Self antigens on cell surfaces
Major histocompatibility complex (MHC): Genes encoding histocompatibility antigens
Human leukocyte antigen (HLA) complex: The group of MHC genes on leukocytes

18. Diseases Related to Specific HLAs
Table 19.3

19. Reactions to Transplantation
Transplants may be attacked by T cells, macrophages, and complement-fixing antibodies.
Transplants to privileged sites do not cause an immune response.
Cornea, testes, brain, heart valves and fetal tissue
Stem cells may allow therapeutic cloning to avoid rejection.
Organ rejection

20. Grafts Autograft: Use of one's own tissue
Isograft: Use of identical twin's tissue
Allograft: Use of tissue from another person
Xenograft product: Use of non-human tissue
Graft-versus-host disease can result from transplanted bone marrow that contains immunocompetent cells

21. Immunosuppression prevents an immune response to transplanted tissues
Cyclosporine suppresses IL-2
Mycophenolate mofetil inhibits T cell and B cell reproduction
Sirolimus blocks IL-2

22. Immune Deficiencies Congenital: Due to defective or missing genes
Selective IgA immunodeficiency
Severe combined immunodeficiency
Acquired: Develop during an individual's life, due to drugs, cancers, infections
Artificial: Immunosuppression drugs
Natural: HIV infections

23. The Immune System and Cancer
Cancer cells possess tumor-specific antigens
Immunological surveillance
Tc cells seek out and recognize cancer cells
Tc cells lyse cancer cells
Figure 19.11

24. Immunotherapy Treatment of cancer using immunologic methods
Tumor necrosis factor, IL-2, and interferons may kill cancer cells
Immunotoxins link poisons with an monoclonal antibody directed at a tumor antigen like ricin
ribosome-inactivating proteins" (RIPs)
Vaccines contain tumor-specific antigens