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.
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.
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