特異性:Tacrolimus (FK-506) Detects FK-506, a macrolide with similar but more potent immunosuppressant activity than cyclosporine. It is a 23-membered lactone produced by the bacteria Streptomyces tsukubaensis. FK-506 inhibits signal transduction and interleukin-2 transcription in CD4+ T helper lymphocytes, and is mainly used after allogenic organ transplatation to reduce organ rejection.