The Immune Response

The Immune Response

• The immune system is designed to recognize and combat foreign invaders, distinguishing them from the body's own cells (self vs nonself)
• Each cell carries specific molecular markers that label it as "self", which determine what makes us unique and distinguishes one person from another
• Any substance or physical structure that can be recognized by the immune system is called an antigen
• Major classes of antigens include proteins, carbohydrates, lipids, and nucleic acids
• Antigens can trigger an immune response, and complex antigens can stimulate full immune activity

Autoimmunity and Immune Balance

• If the immune system loses its ability to distinguish self from nonself, it can launch an aggressive response against the body's own tissues, leading to autoimmune disease
• The immune system maintains a balance of responsiveness, as too little response is ineffective, and too aggressive a response can lead to destruction of bystander tissues
• Regulation of immune function and overall immuno-homeostasis is under the control of multiple factors, including genetic components and environmental cues

Cluster of Differentiation (CD)

• CD refers to proteins found on the surface of cells, each with a unique number for identification
• CD molecules can be specific for one cell or cell lineage, or not
• CD designation is used to characterize cell phenotypes and has identified over 400 individual and unique markers
• CD-specific diagnostic agents are useful for determining protein functions and identifying their distribution in different cell populations

Innate and Adaptive Immunity

• Innate immunity provides the first line of defense against infectious diseases, consisting of physical barriers and biochemical factors
• Innate immune mechanisms exist from birth and include anatomic, physiologic, phagocytic, and inflammatory components
• Adaptive immunity is triggered by the innate immune response and involves a more focused set of reactive molecules and cellular components to combat specific organisms
• Both innate and adaptive components must function in concert to combat and control disease successfully