Host Defense and the Airway Epithelium: Frontline Responses That Protect against Bacterial Invasion and Pneumonia

Table 1

Immunomodulatory roles of type II alveolar epithelial cells.

Role	Component	Function	Ref
Antimicrobial
	Complement	Membrane disruption, opsonization, and inflammation	[6]
	Cathelicidin	Membrane disruption	[6]
	β-defensins	Membrane disruption	[6]
	Immunoglobulin	Complement-mediated lysis, agglutination, and opsonization	[6]
	Lipocalin 2	Iron sequestration	[6]
	Lysozyme	Membrane disruption	[6]
	Nitric oxide	Membrane disruption	[5]
	Surfactant	Agglutination (SpA, SpD), membrane disruption (SpB)	[6]
Inflammation
	TLR2	Recognition of lipoproteins, lipoteichoic acid, and peptidoglycan	[6]
Receptors	TLR4	Recognition of lipopolysaccharide	[6]
	IL-2R	IL-2 receptor	[5]
	TNF-R1	TNFα receptor	[5]
	MHC-I	Antigen presentation to CD8 T cells	[6]
	MHC-II	Antigen presentation to CD4 T cells	[6]
Cytokines and chemokines	IL-1α	Prostaglandin production, induces TNFα	[6]
	IL-1β	Prostaglandin production, induces TNFα	[6]
	IL-4	Th2 Polarization, immunoglobulin production	[5]
	IL-6	T cell recruitment, B cell differentiation	[6]
	IL-8	Neutrophil chemotaxis	[6]
	GRO-α	Neutrophil chemotaxis	[6]
	ENA-78	Neutrophil chemotaxis	[6]
	MIP-2	Neutrophil chemotaxis	[6]
	TNF-α	Vasodilation, neutrophil activation	[6]
	GM-CSF	Granulocyte and monocyte differentiation	[5]
	RANTES	Monocyte and T cell recruitment	[6]
	MCP-1	Monocyte and T cell recruitment	[6]
	IFN-α/β	MHC-I Expression, NK cell activation	[6]
	IFN-γ	Th1 Polarization, macrophage activation	[5]