Key Event Overview
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AOPs Including This Key Event
|AOP Name||Event Type||Essentiality|
|The Adverse Outcome Pathway on binding of FK506-binding protein 12 (FKBP12) by calcineurin inhibitors leading to immunosuppression||KE||Strong|
Level of Biological Organization
How this Key Event works
FK506 is known to suppress T-cell dependent antibody response; however, it has not been reported so far to directly affect B-cells on antibody production. FK506 inhibits the production of multiple classes of cytokines by T cells; among them, IL-4 and IL-13 are B-cell stimulating factors to proliferate, stimulate B cells, and to activate and induce class switch. Suppression of such B-cell-related cytokines deems to be the main factor for the suppression of TDAR by FK506.
How it is Measured or Detected
In vitro: T and B cells isolated from human PBMC were co-cultured with FK506 for 9 days in the presence of polyclonal T cell stimulation, after which supernatants were tested for immunoglobulin IgM and IgG levels by sandwich ELISA (Heidt et al, 2009). Human PBMC were stimulated with anti-CD3/CD28 for 24 h in the presence of FK506. IL-6 produced in the culture supernatants was measured using ELISA (Sakuma et al. 2001b). SKW6.4 cells were cultured with anti-CD3/CD28 stimulated PBMC culture supernatant. After 4 days culture, IgM produced in the culture supernatants was measured by ELISA (Sakuma et al. 2001b). In vivo: Rats are repeated-administered FK506 orally and immunized by KLH, and its serum is examined for T cell-dependent antigen-specific IgM and IgG levels by sandwich ELISA. Mice are repeated-administered FK506 orally and immunized by SRBC, and its spleen cells are examined by plaque forming cell assay (Heidt et al, 2009, Kino et al. 1987, Ulrich et al. 2004). Class switch: T cells derived from human PBMCs were cultured with FK506, and cytokine mRNA levels of B cell stimulatory cytokines such as IFN-gamma, IL-2, IL-4, IL-5, IL-10, and IL-13 produced by T cells are measured by quantitative PCR (Ulrich et al. 2004).
Evidence Supporting Taxonomic Applicability
In the in vitro experiment using peripheral blood mononuclear cells from blood-bank donors, treatment with FK506 revealed to suppress the production of immunoglobulin (Ig) M and G antibodies specific to T-cell dependent antigens (Heidt et al, 2009), and, in human PBMC cultures, FK506 suppressed the production of IL-6 and IgM antibodies in the presence of T-cell activation (Sakuma et al. 2001b). Oral administration of FK506 to mice for 4 days suppresses the response of plaque forming cells (PFC) using splenocyte after intravenous immunization of sheep erythrocytes (Kino et al. 1987). Oral administration of FK506 to rats over a four-week period reduced production of both anti-KLH-IgG and IgM antibodies after subcutaneous immunization of KLH (Ulrich et al. 2004).
 Heidt, S., Roelen, D. L., Eijsink, C., Eikmans, M., van Kooten, C., Claas, F. H. and Mulder, A. (2010). Calcineurin inhibitors affect B cell antibody responses indirectly by interfering with T cell help. Clinical and experimental immunology. 159(2): 199-207.
 Sakuma, S., Kato, Y., Nishigaki, F., Magari, K., Miyata, S., Ohkubo, Y., and Goto, T. (2001b). Effects of FK506 and other immunosuppressive anti-rheumatic agents on T cell activation mediated IL-6 and IgM production in vitro. International Immunopharmacology 1(4): 749-57.
 Kino, T., Hatanaka, H., Hashimoto, M., Nishiyama, M., Goto, T., Okuhara, M., Kohsaka, M., Aoki, H. and Imanaka, H. (1987). FK-506, a novel immunosuppressant isolated from a Streptomyces. I. Fermentation, isolation, and physico-chemical and biological characteristics. Journal of antibiotics. 40(9): 1249-1255.
 Ulrich, P., Paul, G., Perentes, E., Mahl, A., and Roman D. (2004). Validation of immune function testing during a 4-week oral toxicity study with FK506. Toxicology Letters 149(1-3): 123-31.