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