Immunity and Inflammation Overview

Immunity

• Immunity is the body's ability to resist infection and disease.
• It involves a complex network of cells, proteins, and organs working together.
• Two main types of immunity exist: innate and adaptive.
• Innate immunity is the body's first line of defense, providing immediate responses.
• Adaptive immunity develops over time and provides a more specific response to specific pathogens.

Inflammation

• Inflammation is a complex biological response to harmful stimuli, including pathogens, damaged cells, and irritants.
• Characterized by redness, swelling, heat, pain, and often loss of function.
• Its purpose is to eliminate the injurious agent, clear out cellular debris, and initiate tissue repair.
• Involves various chemical mediators, including histamine and cytokines.
• Chronic inflammation can contribute to various diseases.

Histamines

• Histamine is a chemical mediator released by mast cells and basophils.
• Plays a role in inflammatory responses.
• Causes vasodilation and increased vascular permeability.
• Also involved in allergic reactions.

Immune Response

• The immune response is a coordinated reaction of the immune system to foreign substances or pathogens.
• Involves various immune cells and molecules attacking and destroying pathogens.
• Involves both innate and adaptive components.
• Key components are antigen recognition, cell activation, and elimination of the threat.
• Immune response is crucial to protecting the body against diseases.

Antibody Functions

• Antibodies, also known as immunoglobulins (Igs), are critical components of the adaptive immune system.
• Bind to specific antigens (e.g., proteins or carbohydrates on pathogens).
• Neutralize pathogens, preventing them from infecting cells.
• Mark pathogens for destruction by other components of the immune system (opsonization).
• Activate complement proteins.

Antibody Types

• Five main classes of antibodies exist: IgG, IgM, IgA, IgE, and IgD.
• Each class has distinct roles and structures.
  • IgG is the most abundant, crosses the placenta.
  • IgM is the first antibody produced in response to an infection.
  • IgA is found in bodily secretions.
  • IgE is involved in allergic reactions.
  • IgD is less understood, involved in B cell activation.

Antibody Structure

• Antibodies are Y-shaped proteins consisting of two identical heavy chains and two identical light chains.
• The variable regions of the light and heavy chains form the antigen-binding sites.
• The constant regions determine the antibody class (or isotype).
• The structure allows for specific binding to antigens.

Natural Killer (NK) Cells

• NK cells are lymphocytes that function in the innate immune system.
• Kill infected or cancerous cells.
• Recognize and eliminate cells displaying abnormalities without prior sensitization.
• Release cytotoxic granules that induce cell apoptosis.

Leukocytes

• Leukocytes, also known as white blood cells, are crucial components of the immune system.
• Various types, including neutrophils, lymphocytes, monocytes, eosinophils, and basophils, with distinct roles in immune responses and inflammation.
• Involved in fighting infection and inflammation.

Complement Proteins

• Complement proteins are a group of serum proteins that assist antibodies in eliminating pathogens.
• Activated in a cascade-like manner, leading to pathogen lysis, opsonization or inflammation.
• Can cause pathogen lysis (rupturing) directly.
• Enhance the ability of antibodies and phagocytes to clear pathogens.