Overview of Immunology

Definition: Immunology is the branch of biomedical science that deals with the study of the immune system.
Immune System Function: Protects the body against pathogens (bacteria, viruses, fungi, parasites) and foreign substances.

Innate Immunity
- First line of defense.
- Non-specific responses.
- Components:
  - Physical barriers (skin, mucous membranes).
  - Cellular components (phagocytes, natural killer cells).
  - Chemical mediators (complement system, cytokines).
Adaptive Immunity
- Specific responses to pathogens.
- Component:
  - Lymphocytes (B cells and T cells).
  - B cells produce antibodies, provide humoral immunity.
  - T cells are involved in cell-mediated immunity (CD4+ helper T cells and CD8+ cytotoxic T cells).

Recognition: Detection of pathogens through pattern recognition receptors (PRRs).
Activation: Triggering of immune cells and initiation of immune responses.
Response: Elimination of pathogens via phagocytosis, destruction by lymphocytes, or antibody binding.
Memory: Formation of memory cells for quicker response during re-exposure to the same pathogen.

Active Immunity: Immunity that develops after exposure to a pathogen or through vaccination.
Passive Immunity: Immunity gained by receiving antibodies from another source (e.g., maternal antibodies).

Antigens: Molecules that trigger an immune response.
Antibodies: Proteins produced by B cells that specifically target antigens.
Vaccination: Introducing antigens to stimulate the adaptive immune response without causing disease.
Autoimmunity: When the immune system mistakenly attacks the body’s own cells.
Allergies: Exaggerated immune responses to non-pathogenic substances.

Immunodeficiencies: Conditions where the immune system is less active (e.g., HIV/AIDS).
Autoimmune Diseases: Conditions where the immune system targets the body’s own tissues (e.g., rheumatoid arthritis, lupus).
Hypersensitivity Reactions: Excessive immune responses to harmless substances (e.g., allergens).

Hematopoiesis: Formation of blood cells including immune cells from stem cells in bone marrow.
Thymic Selection: Process where T cells mature and are tested for functionality and self-tolerance in the thymus.

Intervention Techniques: Includes immunotherapy, monoclonal antibodies, and gene therapy to enhance or modulate the immune response.
Probiotics and Microbiome: The role of gut health and its impact on the immune system's efficiency.

Innate immunity:
- First line of defense, non-specific.
- Physical barriers: Skin, mucous membranes.
- Cellular components: Phagocytes (engulf pathogens), natural killer (NK) cells (kill infected cells).
- Chemical mediators: Complement system (a group of proteins that helps destroy pathogens), cytokines (signaling molecules).
Adaptive immunity:
- Specific response to pathogens.
- Lymphocytes: B cells (produce antibodies, humoral immunity), T cells (involved in cell-mediated immunity).
  - CD4+ helper T cells: help activate other immune cells.
  - CD8+ cytotoxic T cells: directly kill infected cells.

Recognition: Identifies pathogens with pattern recognition receptors (PRRs).
Activation: Triggers immune cells and starts the immune response.
Response: Eliminates pathogens via:
- Phagocytosis (engulfing and digesting).
- Lymphocyte destruction (T cell killing).
- Antibody binding (neutralizing or marking for destruction).
Memory: Forms memory cells for faster response upon re-exposure.

Active immunity:
- Develops after exposure to a pathogen or vaccination.
- Body generates its own antibodies.
Passive immunity:
- Received from another source (e.g., maternal antibodies).
- Temporary protection.

Antigens: Molecules that trigger the immune response.
Antibodies: Proteins produced by B cells that specifically bind to antigens.
Vaccination: Introduces antigens to stimulate adaptive immunity without causing disease.
Autoimmunity: Immune system attacks the body's own cells.
Allergies: Exaggerated immune responses to non-pathogenic substances (allergens).

Immunodeficiencies: Weakened immune system (e.g., HIV/AIDS).
Autoimmune diseases: Immune system attacks body tissues (e.g., rheumatoid arthritis, lupus).
Hypersensitivity reactions: Excessive immune responses to harmless substances (e.g., allergies).

Hematopoiesis: Formation of blood cells (including immune cells) from stem cells in bone marrow.
Thymic selection: T cells mature and are tested for functionality and self-tolerance in the thymus.

Intervention techniques:
- Immunotherapy: Modifies the immune response.
- Monoclonal antibodies: Target specific antigens.
- Gene therapy: Modifies genes to improve immune function.
Probiotics and microbiome: Gut health influences immune system efficiency.