🏥 Medical Encyclopedia

Immunology

The immune response cascade

Immunology is the branch of medicine and biology that studies the immune system, the body's defense mechanism against pathogens, toxins, and foreign substances.

🛡️ Key Fact: The immune system can recognize up to 10 million different antigens and mounts specific responses to each.

Components of the Immune System

Component	Type	Function
T Lymphocytes (T Cells)	Adaptive immunity	Cell-mediated immunity
B Lymphocytes (B Cells)	Adaptive immunity	Produce antibodies
Natural Killer Cells	Innate immunity	Destroy infected cells
Macrophages	Innate immunity	Phagocytosis, antigen presentation
Dendritic Cells	Innate immunity	Antigen presentation
Antibodies (Immunoglobulins)	Adaptive immunity	Neutralize pathogens

Types of Immunity

Innate Immunity: Non-specific, immediate response (skin, mucus, phagocytes)
Adaptive Immunity: Specific, memory-based response (T cells, B cells, antibodies)
Active Immunity: Produced by the body's own immune response (infection, vaccination)
Passive Immunity: Received antibodies (maternal, antibody therapy)

Immunological Disorders

Autoimmune Diseases: Immune system attacks the body's own tissues (Rheumatoid arthritis, Lupus, Type 1 Diabetes)
Immunodeficiencies: Weakened immune response (HIV/AIDS, SCID)
Allergies: Overreaction to harmless substances (Pollen, food allergies)
Transplant Rejection: Immune response to transplanted organs

"The immune system is the body's most sophisticated defense mechanism." – Dr. Anthony Fauci Immunologist, Former Director of NIAID