Immunology Applications and Disorders

Chapter 18: Practical Applications of Immunology

Key Subjects

  • Vaccines

    • Definition: Biological preparations that provide immunity to a particular disease by stimulating the body’s immune response.

  • Monoclonal Antibodies

    • Definition: Antibodies that are identical and produced from a single clone of cells or a cell line.

  • Agglutination

    • Definition: The clumping of particles, such as cells or microorganisms, in the presence of specific antibodies.

  • Titer

    • Definition: A laboratory test that measures the concentration of antibodies in the blood against a specific antigen.

  • Neutralization

    • Definition: A process where antibodies bind to pathogens or their toxins to inhibit their biological activity.

  • Fluorescent Antibody

    • Definition: Antibodies labeled with fluorescent dyes used to detect the presence of specific antigens in samples using fluorescence microscopy.

Reported Cases of Measles in the United States (1960-2007)

  • Overview of trends in measles cases showing significant decline after the vaccination program was implemented.

  • Graph Details:

    • 500,000 cases reported in 1960

    • Continuous decline reaching approximately 100 cases by 2007

    • Major vaccine licensing events correspond with decreases in reported cases.

Specific Vaccines

  • Types and Names

    • Importance of understanding the different types of vaccines to prevent various diseases.

Production of Vaccines

  • Types of Vaccines:

    • Attenuated Whole-Agent Vaccines (Live): Pathogens that have been weakened so they do not cause disease, e.g., MMR (measles, mumps, rubella) vaccine.

    • Inactivated Whole-Agent Vaccines (Dead): Pathogens that have been killed and cannot cause disease, e.g., Salk polio vaccine.

    • Toxoids: Inactivated toxins from bacteria that stimulate immunity without causing disease, e.g., tetanus vaccine.

    • Subunit Vaccines: Composed of pieces of the pathogen (proteins or polysaccharides) such as purified diphtheria toxoid.

    • Nucleic Acid (DNA) Vaccines: Vaccines that contain DNA or RNA from the pathogen which is taken up by host cells to produce antigens; DNA vaccines are more stable than protein-based vaccines.

More Vaccine Examples

  • Diphtheria: Purified diphtheria toxoid

  • Meningococcal Meningitis: Purified polysaccharide from Neisseria meningitidis

  • Pertussis (Whooping Cough): Killed whole or acellular fragments of Bordetella pertussis

  • Pneumococcal Pneumonia: Purified polysaccharide from 7 strains of Streptococcus pneumoniae

  • Tetanus: Purified tetanus toxoid

  • Haemophilus influenzae type b Meningitis: Polysaccharide conjugated with protein

  • Influenza: Injected inactivated virus or nasally-administered attenuated virus

  • Measles, Mumps, Rubella: All attenuated viruses

  • Chickenpox: Attenuated virus

  • Poliomyelitis: Killed virus

Mechanism of Vaccination

  • Example: H1N1 Vaccine

    • Two types: Nasal (live attenuated) and Shot (inactivated).

    • Both induce memory response leading to T helper (Th) cytokine production.

Monoclonal Antibodies

  • Production:

    • Initiation: A mouse is injected with a specific antigen, triggering B cell response.

    • The spleen is harvested and homogenized to create a cell suspension rich in B cells.

    • B cells are fused with myeloma cells (cancerous B cells) to form hybridoma cells that can produce antibodies indefinitely.

  • Selection Process:

    • Hybrid cells proliferate and are screened for desired antibody production.

    • Selected hybridomas are cultured to yield large quantities of monoclonal antibodies.

  • Applications:

    • Used in diagnostic tests for allergies, infectious diseases, cancer therapy, and treatment of conditions like rheumatoid arthritis.

Techniques Involving Monoclonal Antibodies

  • Agglutination: Utilization of monoclonal antibodies to induce agglutination in cases where particulate antigens are present.

    • Example: Latex agglutination test utilized for detecting pathogens such as Staphylococcus aureus, where clumping indicates positive results.

  • Serological Testing: Techniques like ELISA (Enzyme-Linked Immunosorbent Assay) for detecting antibodies or antigens using labeled antibodies leading to visible color changes as an indicator of the presence of the targeted substance.

Neutralization Reactions

  • Definition: Antibodies eliminate harmful effects by binding to virus particles or exotoxins, rendering them inactive and preventing damage to cells.

  • Visual Representation: Demonstrates the neutralization mechanism illustrating how antibodies block toxin action.

Fluorescent Antibody Techniques

  • Purpose: Sensitive detection of pathogens using fluorescently labeled antibodies under a microscope.

  • Applications include analyzing food and water samples for pathogens such as group A streptococci and examining patient throat specimens.

Examples of Monoclonal Antibodies (Mabs)

  • Muromonab-CD3: Used in kidney transplants

  • Infliximab: Treatment for Crohn’s disease

  • Ibritumomab + Rituximab: For non-Hodgkin’s lymphoma

  • Trastuzumab (Herceptin): Treatment for breast cancer

Types of Monoclonal Antibodies

  • Chimeric Mabs: Genetically modified mouse antibodies with human constant regions.

  • Humanized Mabs: Mainly human antibodies, with minimal mouse components.

  • Fully Human Mabs: Antibodies produced from human genes in mice.

Antibody Response Dynamics

  • IgM Response:

    • Primary antibody response characterized by IgM production upon first and subsequent pathogen exposure.

    • Timeframe visualization of IgM peaks suggesting memory development and secondary response dynamics reflecting increased antibody production.