Chapter 17 & 18 study guide

Immunization and Immune Disorders

Introduction

This study guide covers key concepts from Chapter 17, focusing on immunization strategies and various immune disorders. Understanding these topics is essential for grasping how the immune system can be harnessed to prevent disease and how its dysfunction can lead to pathology.

Immunization

Immunization is the process by which an individual's immune system is fortified against specific pathogens through exposure to antigens. This can be achieved via natural infection or artificial means such as vaccines.

• History of Vaccination: The practice of vaccination began with Edward Jenner's use of cowpox to prevent smallpox. Modern vaccines have evolved to target a wide range of infectious diseases.

• Types of Vaccines:

  • Attenuated (Live) Vaccines: Contain weakened pathogens that replicate without causing disease. Example: Measles, Mumps, Rubella (MMR) vaccine.

  • Inactivated (Killed) Vaccines: Contain pathogens that have been killed. Example: Polio (Salk) vaccine.

  • Toxoid Vaccines: Contain inactivated toxins produced by pathogens. Example: Tetanus vaccine.

  • Subunit and Conjugate Vaccines: Contain only parts of the pathogen, such as proteins or polysaccharides. Example: Haemophilus influenzae type b (Hib) vaccine.

• Advantages and Disadvantages:

  • Live vaccines often provide longer-lasting immunity but may not be suitable for immunocompromised individuals.

  • Inactivated vaccines are safer but may require booster doses.

• Herd Immunity: When a significant portion of a population is immune, the spread of disease is limited, protecting those who are not immune.

• Risks and Side Effects: Most vaccines are safe, but rare adverse reactions can occur, such as allergic responses.

Immune Disorders

Immune disorders arise when the immune system malfunctions, either by overreacting (hypersensitivity), attacking self-tissues (autoimmunity), or failing to respond adequately (immunodeficiency).

• Hypersensitivity Reactions:

  • Type I (Immediate): Allergic reactions mediated by IgE antibodies. Example: hay fever, anaphylaxis.

  • Type II (Cytotoxic): Antibody-mediated destruction of cells. Example: hemolytic disease of the newborn.

  • Type III (Immune Complex): Deposition of antigen-antibody complexes. Example: serum sickness.

  • Type IV (Delayed): T-cell mediated responses. Example: contact dermatitis, tuberculin reaction.

• Autoimmune Diseases:

  • Occur when the immune system attacks self-antigens. Examples include Type I diabetes mellitus and rheumatoid arthritis.

• Immunodeficiency Diseases:

  • Primary (Congenital): Genetic defects affecting immune function. Example: Severe Combined Immunodeficiency (SCID).

  • Secondary (Acquired): Result from external factors such as infections (e.g., HIV/AIDS) or immunosuppressive drugs.

• Transplantation Immunology:

  • Transplants can be rejected due to immune recognition of non-self antigens. Immunosuppressive therapy is used to prevent rejection.

Immune Testing

Immune testing involves laboratory methods to detect the presence of antigens or antibodies, aiding in diagnosis and monitoring of diseases.

• Serological Tests: Use antibodies to detect antigens in patient samples. Examples include ELISA and Western blot.

• Immunofluorescence: Uses fluorescent-labeled antibodies to visualize antigens in tissues or cells.

• Applications: Diagnosis of infectious diseases, autoimmune disorders, and monitoring vaccine efficacy.

Table: Types of Hypersensitivity Reactions

Type	Mechanism	Example
I (Immediate)	IgE-mediated, mast cell degranulation	Allergic rhinitis, anaphylaxis
II (Cytotoxic)	IgG/IgM antibodies against cell surface antigens	Hemolytic anemia, transfusion reactions
III (Immune Complex)	Antigen-antibody complex deposition	Serum sickness, systemic lupus erythematosus
IV (Delayed)	T-cell mediated	Contact dermatitis, tuberculin reaction

Key Equations

• Vaccine Efficacy: $\text{Vaccine Efficacy} = \frac{(\text{Attack Rate in Unvaccinated} - \text{Attack Rate in Vaccinated})}{\text{Attack Rate in Unvaccinated}} \times 100$

Examples and Applications

• Example: The MMR vaccine protects against measles, mumps, and rubella by stimulating the production of memory cells specific to these viruses.

• Application: ELISA is commonly used to diagnose HIV infection by detecting antibodies against the virus in patient serum.

Additional info: These notes expand on the provided study guide topics to ensure completeness and academic clarity for exam preparation.