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