Adaptive Immunity: Specific Defenses of the Host

The Adaptive Immune System

Innate (nonspecific) Resistance (Native Immunity) - the genetically predetermined resistance to certain diseases

Factors Affecting Resistance:

Adaptive immunity is the ability of the body to specifically counteract foreign organisms or substances called antigens.

Adaptive immunity results from production of specialized lymphocytes and antibodies.

The Duality of the Immune System

Humoral (Antibody-Mediated) Immunity

Found in body fluids.

Antibodies made by plasma cells (activated B lymphocytes) in response to specific antigen.

Primarily defends against bacteria, viruses, and toxins in blood and lymph - extracellular antigens.

Cell-Mediated Immunity

T cells have antigen receptors but don’t make antibodies – lyse target cells directly.

Primarily responds against intracellular viruses, multicellular parasites, transplanted tissue and cancer cells