Overview of Immunology

Definition: Immunology is the branch of biomedical science that deals with the immune system and its functions, diseases, and mechanisms of resistance to infection.
Key Areas:
- Innate Immunity
- Adaptive Immunity
- Immunodeficiencies
- Autoimmunity
- Vaccination and Immunotherapy

Cells:
- Lymphocytes: B cells (produce antibodies) and T cells (cell-mediated immunity).
- Phagocytes: Macrophages and neutrophils that engulf pathogens.
- Natural Killer (NK) Cells: Attack and destroy infected or cancerous cells.
Organs:
- Primary: Bone marrow (B cell maturation) and thymus (T cell maturation).
- Secondary: Lymph nodes, spleen, and mucosal-associated lymphoid tissue (MALT).
Molecules:
- Antibodies: Proteins that specifically bind to antigens to neutralize them.
- Cytokines: Signaling molecules that mediate and regulate immunity.
- Complement System: A group of proteins that enhance immune responses.

Innate Immunity:
- First line of defense, non-specific.
- Includes barriers (skin, mucous membranes), cells (phagocytes), and inflammation.
Adaptive Immunity:
- Specific and involves memory cells for long-lasting protection.
- Two types:
  - Humoral Immunity: Mediated by B cells and antibodies.
  - Cell-Mediated Immunity: Involves T cells targeting infected or cancerous cells.

Recognition: Immune cells detect pathogens via pattern recognition receptors (PRRs).
Activation: Lymphocytes are activated upon encountering their specific antigens.
Effector Phase: Activated B cells produce antibodies; T cells kill infected cells or help B cells.
Memory Phase: Formation of memory cells that allow quick response to future exposures of the same pathogen.

Immunodeficiencies: Conditions resulting in inadequate immune responses (e.g., HIV/AIDS).
Autoimmune Diseases: The immune system attacks its own cells (e.g., rheumatoid arthritis, lupus).
Allergies: Exaggerated immune responses to harmless substances (e.g., pollen, peanuts).

Purpose: To induce immunity without causing disease by exposing the immune system to weakened or inactivated pathogens.
Types:
- Live attenuated vaccines
- Inactivated vaccines
- Subunit, recombinant, or conjugate vaccines

Definition: Treatment that enhances or manipulates the immune response to combat diseases, especially cancer.
Types:
- Monoclonal antibodies
- Immune checkpoint inhibitors
- CAR T-cell therapy

Antigen: Any substance that triggers an immune response.
Pathogen: A disease-causing agent, such as bacteria, viruses, fungi, or parasites.
Homeostasis: Balance of immune response to prevent overactivity or inactivity.

Inflammation: The body's response to injury or infection, characterized by swelling, redness, heat, and pain.
Tolerance: The immune system's ability to not attack the body’s own tissues.
Clonal Selection: The process by which an antigen selectively binds to and activates specific B or T cells.

The study of the immune system, its functions, diseases, and how it protects us from infection.
Two main branches: innate and adaptive immunity.
Addresses immunodeficiencies, autoimmune diseases, and vaccination and immunotherapy.

Cells:
- Lymphocytes:
  - B cells produce antibodies for humoral immunity.
  - T cells mediate cell-mediated immunity.
- Phagocytes:
  - Macrophages and neutrophils engulf pathogens.
- Natural Killer (NK) Cells: destroy infected or cancerous cells.
Organs:
- Primary:
  - Bone marrow matures B cells.
  - Thymus matures T cells.
- Secondary:
  - Lymph nodes, spleen, and mucosal-associated lymphoid tissue (MALT) house immune cells and filter pathogens.
Molecules:
- Antibodies: Proteins that neutralize pathogens by binding to specific antigens.
- Cytokines: Signaling molecules that regulate and mediate immune responses.
- Complement System: Proteins that enhance immune responses.

Innate Immunity:
- The first line of defense, non-specific.
- Includes barriers (skin, mucous membranes), phagocytic cells, and inflammation.
Adaptive Immunity:
- Specific, learned, and creates a memory for long-lasting protection.
- Types:
  - Humoral Immunity: B cells and circulating antibodies.
  - Cell-Mediated Immunity: T cells targeting infected or cancerous cells.

Recognition: Immune cells use pattern recognition receptors (PRRs) to detect pathogens.
Activation: Lymphocytes are activated when they encounter their specific antigens.
Effector Phase:
- Activated B cells produce antibodies.
- Activated T cells kill infected cells or help B cells.
Memory Phase: Memory cells are formed for quick responses to future exposures of the same pathogen.

Immunodeficiencies:
- Deficient immune responses, leaving individuals vulnerable to infections (e.g., HIV/AIDS).
Autoimmune Diseases:
- The immune system attacks its own cells (e.g., rheumatoid arthritis, lupus).
Allergies:
- Exaggerated immune responses to harmless substances (e.g., pollen, peanuts).

Purpose: Induce immunity without causing disease by exposing the immune system to weakened or inactivated pathogens.
Types:
- Live attenuated vaccines: Contain weakened versions of the pathogen.
- Inactivated vaccines: Contain killed versions of the pathogen.
- Subunit, recombinant, or conjugate vaccines: Use specific components of the pathogen, like proteins or antigens.

Definition: Treatments that enhance or manipulate the immune response to fight diseases, especially cancer.
Types:
- Monoclonal antibodies: Target specific cells or molecules involved in disease.
- Immune checkpoint inhibitors: Block inhibitory signals, allowing the immune system to more effectively fight cancer cells.
- CAR T-cell therapy: Engineered T cells with receptors that target cancer cells for destruction.

Antigen: Any substance that triggers an immune response.
Pathogen: A disease-causing agent, such as bacteria, viruses, fungi, or parasites.
Homeostasis: Balance of immune response to prevent overactivity or inactivity.

Inflammation: The body's response to injury or infection, characterized by swelling, redness, heat, and pain.
Tolerance: The immune system's ability to not attack the body’s own tissues.
Clonal Selection: The process by which an antigen selectively binds to and activates specific B or T cells.