Effects of the malononitrilamide FK778 on immune functions in vitro in whole blood from non-human primates and healthy human volunteers.
BACKGROUND
FK778, a malononitrilamide analog of leflunomide, is currently being investigated for use in clinical transplantation.


METHODS
Whole blood from cynomolgus monkeys (n=4) and healthy human volunteers (n=4) was incubated with different concentrations of FK778 and stimulated with mitogens in culture medium. Lymphocyte proliferation was assessed by tritium-labeled thymidine incorporation and by flow-cytometric analysis of expression of proliferating cell nuclear antigen on cells in S/G(2)M phase. Flow cytometry was also used to assess expression of T and B lymphocyte activation surface antigens and production of intracellular cytokines by T cells.


RESULTS
Not only lymphocyte proliferation, but also expression of various T cell surface antigens (CD25, CD11a, CD95, CD154) was suppressed by FK778. Fifty percent effective concentration values for the different immune functions were lower in human blood than in blood from cynomolgus monkeys.


CONCLUSIONS
FK778 inhibits multiple immune functions. Their flow cytometric evaluation can be used to assess the effects of the drug in vivo.
Bîrsan
Tudor
T
Department of Cardiothoracic Surgery, Stanford University School of Medicine, 300 Pasteur Drive, Falk CVRB, Stanford, CA 94305-5407, USA.
Dambrin
Camille
C
Klupp
Jochen
J
Stalder
Mario
M
Fitzsimmons
William E
WE
Morris
Randall E
RE
D000480:Alkynes; D000818:Animals; D001681:Biological Assay / Q000379:methods; D001774:Blood Chemical Analysis; D002455:Cell Division / Q000187:drug effects; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007555:Isoxazoles / Q000494:pharmacology*; D008213:Lymphocyte Activation / Q000187:drug effects*; D008214:Lymphocytes / Q000187:drug effects*; D008297:Male; D009570:Nitriles; D018809:Proliferating Cell Nuclear Antigen / Q000096:biosynthesis
D000480:Alkynes; D007555:Isoxazoles; D009570:Nitriles; D018809:Proliferating Cell Nuclear Antigen; C115284:2-cyano-3-hydroxy-N-(4-(trifluoromethyl)phenyl)-2-hepten-6-ynamide