Immunologic activation

In immunology, activation is the transition of leucocytes and other cell types involved in the immune system. On the other hand, deactivation is the transition in the reverse direction.^[1] This balance is tightly regulated, since a too small degree of activation causes susceptibility to infections, while, on the other hand, a too large degree of activation causes autoimmune diseases.

Factors

Activation and deactivation results from a variety of factors, including cytokines, soluble receptors, arachidonic acid metabolites, steroids, receptor antagonists, adhesion molecules, bacterial products and viral products.^[1]

Overview of activating and deactivating factors.

	Activation	Deactivation
Cytokines	IFN-γ GM-CSF M-CSF IL-6 TNF-α MIF CCL2	IL-4 IL-10 IL-13 TGF-β
Soluble receptors		sIL-1R sIL-6R sTNFR sCD14
Arachidonic acid metabolites	PGE2 LTB4
Steroids		Corticosteroids
Receptor antagonists		IL-1Ra
Adhesion molecules	β2-integrins Fc receptors CD14 P-selectin CD45
Bacterial products	LPS fMetLeuPhe
Viral products	dsRNA	BCRF1 (IL-10-homologue) T2 (sTNFR-homologue) M-T7 (sINF-γR-homologue)

See also

• Immune system