Leukocyte chemotactic activity of cyclophilin

During the purification of eosinophil chemotactic factors synthesized by the uterus in response to estrogen we isolated a protein having an N-terminal (15 amino acids) sequence identical to that of rat cyclophilin. Our data demonstrate that cyclophilin, a cytosolic protein isolated from bovine thymocytes, which specifically binds the immunosuppressive drug cyclosporin A, as well as recombinant human cyclophilin, displays eosinophil chemotactic activity. In addition to its chemotactic activity, cyclophilin stimulated the release of peroxidase activity from eosinophils. Maximal chemotactic activity of cyclophilin was achieved at a concentration of approximately 10 nM. At similar concentrations cyclophilin was also able to stimulate the migration of neutrophils. This chemotactic activity could be prevented by the addition of cyclosporin A, but not by a nonimmunosuppressive analog (1-fur-furyl-cyclosporin A) at similar concentrations. This chemotactic activity may represent an additional mechanism by which immunosuppressive drugs function to prevent tissue rejection.