Table 2.

Innate versus adaptive immunity

	Innate immune system	Adaptive immune system
Characteristics	Discriminates self from non-self	Discriminates self from non-self
	General protection	Antigen specific
	Early phase of host response; immediate	Late phase of host response
	Does not require prior exposure	Requires prior exposure
	Response does not alter on repeated exposure; no memory	Response improves with successive exposures; immunological memory
Components
Physical and chemical barriers	Skin, mucous and mucous membranes, tears, saliva, nasal secretions, sweat, defensins, surfactant	Lymphocytes at surfaces
Humoral components	Complement, coagulation system, lactoferrin, transferrin, lysozyme, interleukin-1, interferons	B lymphocytes
Cellular components	Monocyte-derived macrophages, dendritic cells, mast cells, natural killer cells, granulocytes (neutrophils, eosinophils, basophils)	T lymphocytes