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Specific Defenses of the host

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					Specific Defenses of the host

• Innate resistance • Immunity: ability of the body to resist pathogens
– Due to production of specific lymphocytes and antibodies

• Acquired immunity
– Naturally – active immunity – get it, get over it – Passive immunity – Mother to child, AB from mother (short term)

Artificially acquired immunity
• Vaccination • Antiserum • Gamma globulin (IgG purified)

• Antigen, anything that can cause an immunological response
– Examples

Humoral vs.. cell mediated immunity
• Humoral is serum immunity • Cell mediated depends on T cells

Antibody Structure
• The monomer is bivalent • 4 ppt chains, 2 light and 2 heavy • All contain a V region where antibody binding occurs • Y or T shaped know where ab binds, know constant region. • Fc or constant region binds to host cell or complement.

Classes of Immunoglobulin
• IgG serum, passive immunity, neutralize, precipitate, opsonize • IgM 5monomers on a chain, agglutination and complement • IgA monomer in serum, dimmers in mucus, protects outer surfaces. • IgD antigen receptors on B cells • IgE antigen receptors on mast cells and basophiles.

• Apoptosis: programmed cell death, Lymphocytes that are no longer needed destroy themselves. • Clonal selection: during fetal development, self reacting AB is destroyed. During sickness more AB is produced (will review later)

Types of WBC

Results of antigen binding
• • • • • Neutralize Opsonizaiton Agglutination Fixing complement Precipitation

Immunological memory
• AB titer • Plasma cells • Memory cells

Monoclonal Antibodies
• Immortal cells that produce an antibody that binds to one haptin.

Antibodies can now be manufactured
• Used to tread diseases like cancer • How are antibodies treated so that they do not produce an immune response?

All of the previous activities are due to B cells.

T cells and cell mediated Immunity
• Differentiate in the thymus gland (and others) • Classified by cell surface receptors (CD4) • Binds to antigen and APC by MHC

Practical applications of Immunology
• Vaccines
– Heard immunity: if > 85% are immune to a disease, the pathogen has difficulty spreading

• Types
– Attenuated whole agent – non pathogenic – Inactivated whole agent – dead – Toxoids – inactivated toxin – Subunit vaccine –purified protein – Conjugated vaccine – DNA vaccine – MHC1 associated responses

How to make vaccines
• • • • Animals Cell culture Chick embryos Recombinant vaccines are much safer

Diagnostic immunity

Disorders of the Human immune system

Defects
• • • • • Hay fever Transplant rejection Autoimmunity Infection carriers

Hypersensitivity
• Rx that lead to tissue damage • Occur when person is sensitized • 4 types

Type 1 anaphylactic
• Excess IgE binds to mast cells and basophiles • IgE receptors on membrane cause release of histamine, leukotrienes, prostaglandin’s • Very rapid may occur in minutes • Localized in hives, hay fever, asthma • Can be tested with skin pricks • Immuno desensitization IgG blockers

Type I (Anaphylactic) Reactions
• Involve IgE antibodies • Localized: Hives or asthma from contact or inhaled antigens • Systemic: Shock from ingested or injected antigens
Figure 19.1a

Type I (Anaphylactic) Reactions
• Skin testing • Desensitizatio n

Figure 19.3

Type II cytotoxic
• Involve IgM, IgG and complement • Antibodies bind to cells complement and macrophage break cells.
– Type of Rx with blood cells A, B R plus and R minutes

• Drug induced cytotoxic effects
– Drugs bind to cells cause Rx

ABO Blood Group System

Table 19.2

Hemolytic Disease of the Newborn

Figure 19.4

Drug-induced Thrombocytopenic Purpura

Figure 19.5

Type III immune complex
• IgG and soluble antigen lodge in basement membrane • Results in inflammation • Serum sickness • Glomerulomephritis

• IgG antibodies and antigens form complexes that lodge in basement membranes.

Type III (Immune Complex) Reactions

Figure 19.6

Type IV cell mediated
• A delayed reaction • Sensitized T cells respond to antigen • Cytokines attract macrophage that damage • Tuberculin skin test, contact dermatitis

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

Figure 19.8

Autoimmune disease
• From loss of self tolerance • Self tolerance occurs during fetal development
– Clonal deletion – Clonal anergy

• • • • • •

Graves disease Myasthenia gravis Systemic lupus Rheumatoid arthritis Hashimotas disease Insulin dependent diabetes

Autoimmune Diseases
• Type I — Due to antibodies against pathogens • Type II — Antibodies react with cellsurface antigens • Type III (Immune Complex) — IgM, IgG, complement immune complexes deposit in tissues • Type IV — Mediated by T cells

• Diseases related to human leukocyte Antigen HLA
– 25 loci with 100 alleles each

Transplantation reactions
• Transplants are attacked by T cells, macrophage and complement • Privileged tissue and sites do not have reactions • 4 types autographs, isograph allograph xenograph • Transplanted bone marrow – graft vs. host disease • Cyclosporin (IL2 blocker) an immunosuppressive drugs

Immune Deficiencies
• Congenital • acquired

Cancer control
• Normal cells that divide uncontrollably • Immunological surveillance usually prevents • Tc cells kill cancerous cells • Sometimes cancer cells can escape immunity

• Cancer cells possess tumor-specific antigens • TC cells recognize and lyse cancer cells • Cancer cells may lack tumor antigens or kill TC cells

The Immune System and Cancer

Figure 19.11

Immunotherapy
• Cytokines (Tumor Necrosis factor) • Immunotoxins • Vaccines against cancer antigens

Aids
• Origin central Africa

HIV infection
• AIDS is the last stage of HIV infection • Blood typing website • http://www.nobel.se/medicine/educational/l andsteiner/index.html


				
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