Overview of the Immune System

Teaching objectives Recognize the significance of the immune system What is the role/purpose? What are the mechanisms of protection? Distinguish between the innate and adaptive immune response What are the key features differentiating these two arms of the immune system?

Overview of the immune system Purpose: Protection from pathogens Intracellular (viruses, some bacteria and parasites) Extracellular (most bacteria, fungi, and parasites) Eliminate modified or altered “self” Cancer or transformed cells Methods of defense: mechanical, cellular, humoral

Overview of the immune system Innate (nonspecific) 1st line of defense Cellular components Humoral components Adaptive (specific) 2nd line of defense

Cells of the immune system Myeloid cells Granulocytic Neutrophils Basophils Eosinophils Monocytic Macrophages Kupffer cells Dendritic cells Lymphoid cells T cells Helper cells Suppressor cells Cytotoxic cells B cells Plasma cells NK cells

Phases of the immune response Pathogen recognition Innate response is the same to repeated exposures of the same pathogen Adaptive response matures over time; repeated exposure leads to faster response Pathogen removal Early response: innate Later response: lymphocytes generate adaptive immune response and memory

Comparison of innate and adaptive immune response Innate immunity No time lag Not antigen specific No memory Adaptive immunity A lag period Antigen specific Development of memory

Effects of the immune system Beneficial Protection from invader Elimination of altered self Detrimental Inflammation (local damage and discomfort) Damage to self (hypersensitivity or autoimmunity)

Balance Disease = (bolus of infection x virulence)/immunity infection