Immune System

“Do I still have to go to school doc?”

What Does My Immune System Do?

• Discriminates between “self” and “foreign”• Response by immune system protects us– INVADERS!!!! ATTACK!!!

Important Terms & Their Definitions• Antigen Anything causing an immune response, usually foreign

material but may be our own tissues. • Pathogen Any disease causing micro-organism. • Chemokines Molecules released by pathogens and infected tissues to

attract cells of the immune system. • Cytokines Signaling molecules released by one cell to cause a response

in another. Signaling is extremely important in our immune response.• Innate Immunity Protection that is always present. • Adaptive Immunity Protection that arises by an immune response• B Cells Make antibodies for antigens, perform role of APC, and

develop into memory B cells• Helper T Cells (Th) When activated, they divide rapidly and secrete

cytokines• Cytotoxic T Cells (Tc) Induce the death of cells

• Phagocytes Cells that engulf the foreign material

Process

• Our body gets infected by pathogen– Bacteria, Virus, Fungus

• The antigens of the microbe are recognized • The body response is either “Humoral” or

“Cell-Mediated”

Humoral Immunity

• Free antigens activate B Cells into Plasma Cells– Plasma cells secrete antibodies

• These antibodies defend against pathogens by binding to antigens and making the pathogens easier targets for being destroyed by phagocytes

Cell Mediated Immunity

• Infected cells displays antigens• Antigens displayed by infected cells activate

Cytotoxic T-cells (TC) when bounded

• The activated T-cell (TC) releases chemicals that cause pores in the infected cell

• Water and ions enter infected cell and cell gets destroyed

The Role of Helper T-Cells (Th)

• Antigen can be engulfed by macrophages• Macrophages will present the antigen on their

surface• Helper T-cells are stimulated and differentiate• Helper T-cells secrete cytokines that stimulate

either B-cells or Cytotoxic T-cells

Secondary Response

• Memory cells are created to initiate a quicker secondary response if antigen is presented in body again

• Mimic the same type of B-cell or T-cell but have a higher ability to bind and recognize antigen