Protopic
The mechanism of action of tacrolimus in atopic dermatitis is not fully understood. While
the following have been observed, the clinical significance of these observations in atopic
dermatitis is not known. Via its binding to a specific cytoplasmic immunophilin (FKBP12),
tacrolimus inhibits calcium-dependent signal transduction pathways in T cells, thereby
preventing the transcription and synthesis of IL-2, IL-3, IL-4, IL-5 and other cytokines such as
GM-CSF, TNF-α and IFN-γ. In patients with atopic dermatitis, improvement of skin lesions
during treatment with tacrolimus ointment was associated with reduced Fc receptor
expression on Langerhans cells and a reduction of their hyperstimulatory activity towards T
cells. Tacrolimus ointment does not affect collagen synthesis in humans.