Antibodies and Immunotherapy

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Antibodies and Immunotherapy

• Core 218
• Spring 2007

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Medical Therapies

• Antibiotics
• Recombinant Medicines
• Immunotherapy
• Somatic Gene Therapy
• Germ-Line Therapy

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The Immune Response

• The immune response is the series of cellular and
  humoral (blood) changes that occur in an animal
  to deal with an invasion by foreign organisms or
  substances that are potentially harmful to the
  body, or to deal with altered host cells.

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From http//www.healthscout.com/ency/1/ImagePage
s/8932.html
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Immune Response Involves

• Cell mediated immunity.
• T-cells produced by stem cells in the bone marrow
  that function as helper cells (TH), killer cells
  (CTL), or down regulates other cells (TS).
• Humoral (blood) immunity.
• Lymphoid tissues
• Primary
• Thymus T-cell maturation.
• Bone marrow B-cell maturation.
• Secondary
• Lymph nodes Harbors both T-cells (internal) and
  B-cells (cortex).
• Spleen similar to lymph nodes.

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http//www.healthscout.com/ency/1/ImagePages/9478.
html
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Antibodies

• Antibodies are proteins called immunoglobulins.
  They are produced by the immune system of
  vertebrates in response to foreign substances
  that might be a threat to the body such as
  chemicals, viruses, fungi, toxins, etc.
  Substances that elicit the immune response are
  called antigens.

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Antigens

• Antigens are molecules that elicits a specific
  immune response in an animal.
• Antigens are
• Usually large molecules, greater than 10,000
  Daltons in molecular weight.
• Structurally complex, i.e., proteins.
• Accessible to the immune system.
• Foreign (not recognized as self).

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Antibodies

• Each antibody uniquely binds to a specific
  antigen.
• Two identical heavy and light chains.

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Ribbon image of an IgG molecule. From
http//www.antibodyresource.com/gallery.html
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How Are Antibodies Produced

• Inoculate animal
• Wait
• Inoculate animal again
• Bleed, check titer
• Collect immune sera
• Remove red blood cells
• Purify antibodies

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Memory Response
From http//www.cehs.siu.edu/fix/medmicro/genimm
.htm
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Antibody Categories

• Polyclonal antibodies are a mixture of
  immunoglobulin molecules, produced in animals,
  secreted against a specific antigen, each
  recognizing a specific epitope.
• Monoclonal antibodies are immunoglobulin
  molecules that are produced from hybridomas, that
  are secreted, each recognizing a specific epitope.

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From http//cellbio.utmb.edu/cellbio/membrane_in
tro.htm
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From http//encarta.msn.com/media_461540240_7615
88811_-1_1/Producing_Monoclonal_Antibodies.html
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Hybridomas

• A cell that results from the chemical combination
  of an antibody producing B cell with a myeloma
  cell.
• B-cell produces specific antibody.
• Myeloma cell, can live indefinitely and is an
  antibody secreting cell.

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Use of Monoclonal Antibodies

• Diagnostic Tests.
• Home pregnancy kits target chorionic
  gonadotropin.
• HIV detect antibodies against HIV.
• Heart damage assessment.
• Detection of toxins, pathogens.
• Therapy
• Passive immunotherapy, payload delivery
• Active immunotherapy

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Serological Methods for Disease Detection

• Enzyme-Linked Immunosorbent Assay.
• Developed in the 1970s for virus detection.
• Eva Engvall, Peter Perlmann, Univ. of Stockholm.
• Components
• Immobile solid substrate.
• Antibody
• Antibody-enzyme conjugate

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Diagram of an ELISA Reaction
Antibody-Antigen specific attachment, excess and
non-specific antigen lost.
Substrate conversion
Add Antigen
Antibody2-Enzyme conjugate
S
S
Attachment of the antibody1 to a solid substrate
Add colorimetric substrate
Plastic (polystyrene) well
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ELISA

• Attachment of specific antibody
• Wash
• Add solution containing antigen
• Wash
• Add second antibody-enzyme (alkaline phosphatase
  or horseradish peroxidase).
• Wash
• Add substrate
• Stop reaction

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Monoclonal Therapies

• Naked monoclonal antibodies
• Binds directly to cancer cells making them
  visible the immune system.
• Bind to cancer cell receptors that trigger rapid
  growth.
• Conjugated monoclonal antibodies.
• Antibodies joined to a chemotherapy drug,
  radioactive particle, or toxin.

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Monoclonal Therapies

• Pros
• Side effects less severe than standard
  chemotherapy.
• Cons
• Recognized as foreign, second dose less
  effective.
• May attach to the wrong thing.
• Attached groups may fall off.
• Effective for the short term, tumors may occur.

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Active Immunotherapy

• Active immunotherapy is the use of vaccines to
  stimulate an immune response that directly
  targets the tumor antigens.
• Tumors are immunogenic.
• New and developing area.
• Types
• Peptide and protein vaccines.
• Tumor cell vaccines.
• Viral vectors and plasmid vaccines.

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Review

• What are antibodies?
• What prevents us from infections?
• What is a hybridoma?
• What is a monoclonal antibody?
• What is a polyclonal antibody?
• What is one biotechnological use of antibodies?