Ascomycin

Ascomycin, also called Immunomycin, FR-900520, FK520, is an ethyl analog of tacrolimus (FK506) with strong immunosuppressant properties. It can be used to treat autoimmune diseases and skin diseases, and can help prevent rejection after an organ transplant.

Ascomycin acts by binding to immunophilins, especially macrophilin-12. It appears that Ascomycin inhibits the production of Th1 (interferon- and IL-2) and Th2 (IL-4 and IL-10) cytokines. Additionally, ascomycin preferentially inhibits the activation of mast cells, an important cellular component of the atopic response. Ascomycin produces a more selective immunomodulatory effect in that it inhibits the elicitation phase of allergic contact dermatitis but does not impair the primary immune response when administered systemically.

Ascomycin is produced by the fermentation of Streptomyces hygroscopicus.

Related compounds
Tacrolimus, Pimecrolimus