title: The immunosuppressive agent FK506 inhibits in vitro expression of membrane-bound and soluble interleukin-2 receptors on resting but not on activated human lymphocytes.
abstract: FK506 is a recently introduced immunosuppressive agent synthesised by the microorganism Streptomyces tskubaensis. It has been found to be more potent than Cyclosporin A in inhibiting T cell activation. We investigated its effects on the expression of membrane bound as well as soluble interleukin-2 receptors on human lymphocytes. The membrane-bound IL-2 receptor expression was inhibited by FK506 in resting lymphocytes at a concentration of 1 pmol/l. At 10 nmol/l no further inhibition was seen. In activated lymphocytes FK506 exerted no inhibitory effect on the IL-2 receptor expression. The release of soluble IL-2 receptor showed a pronounced decline in the concentration interval between 10 pmol/l and 0.1 nmol/l. Above a concentration of 10 nmol/l, no further decrease was seen. In activated lymphocytes the expression of soluble IL-2 receptors was unaffected by FK506 incubated up to 72 h. Pretreatment of the lymphocytes with the compound did not further depress the expression of the membrane-bound or the soluble receptor. Our results also indicate that the expression of the membrane-bound receptor is more sensitive to the drug than the soluble form of the receptor.
authors.affiliation: University of Lund, Department of Medical Microbiology, Sweden.
authors.forename: H
authors.initials: H
authors.lastname: Karlsson
authors.forename: L
authors.initials: L
authors.lastname: Truedsson
authors.forename: L
authors.initials: L
authors.lastname: Nässberger
mesh_terms: D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D006801:Humans; D008213:Lymphocyte Activation / Q000187:drug effects*; D008565:Membrane Proteins / Q000378:metabolism; D015375:Receptors, Interleukin-2 / Q000276:immunology / Q000378:metabolism*; D013601:T-Lymphocytes / Q000187:drug effects*; D016559:Tacrolimus / Q000494:pharmacology*
chemical_list: D008565:Membrane Proteins; D015375:Receptors, Interleukin-2; D016559:Tacrolimus