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Adaptive Immunity: Specific Defenses of the host Ch 17

• 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)

Dual Nature of Adaptive Immunity

Figure 17.8

Dual Nature of Adaptive Immunity • T and B cells develop from stem cells in red bone marrow • Humoral immunity – B cells mature in the bone marrow • Chickens: Bursa of Fabricius

– Due to antibodies

• Cellular immunity – Due to T cells – T cells mature in the thymus ANIMATION Humoral Immunity: Overview

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.

Epitopes

Haptens: example penicillin

Figure 17.2

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

Clonal Selection and differentiation of B cells

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.

Production of Monoclonal AB (fig 18.2)

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 (ch 19) • 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

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

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

Types of T cells • Classified by certain glycoproteins on surface (clusters of differentiation (CD)) • Th –T helper-CD4 – Recognise an antigen presented on the surface of a macrophage and activate it.

• Tc – Cytotoxic T cells –CD8 – When activated by cytokines from the Th cell will change to kill self altered cells

• Tr – Regulatory T cells – (turn down immune response)

Cytotoxic T cells are transformed into CTL’s by a cell with markers on it.

The MHC antigen complex induces a toll-like receptor

Organisms like large paracites that are too large for ingestion by phagocytic cells must be attacked externally