Immunosuppressive activity of cyclosporine metabolites compared and characterized by mass spectroscopy and nuclear magnetic resonance.
Eight cyclosporine (CsA) metabolites were isolated from the urine of renal-transplant patients by high-pressure liquid chromatography. Structure and purity of the metabolites were assessed by fast atomic bombardment/mass spectroscopy, by proton nuclear magnetic resonance (NMR), and, when the quantity of metabolites permitted, by 13C-NMR. The immunosuppressive activities (I) of the metabolites were tested in three separate in vitro systems: primary and secondary mixed lymphocyte reactions as well as by a mitogen-stimulated system. The I, as measured by comparing the concentration of each metabolite required for 50% inhibition of incorporation of [3H] thymidine, varied among the assay systems, as did the ranking of I among the test systems. In general, the I of most metabolites in all assay systems were less than 10% of that for CsA. Metabolites with single modifications exhibited the greatest I; e.g., that of M-17 was congruent to 16% of that of CsA (potency ratio 0.16) in a secondary mixed lymphocyte reaction. The significance of these findings in relation to therapeutic monitoring of CsA is discussed.
Copeland
K R
KR
Department of Clinical Chemistry, Health Sciences Clinical Research Centre, Winnipeg, Manitoba, Canada.
Yatscoff
R W
RW
McKenna
R M
RM
D002851:Chromatography, High Pressure Liquid; D003524:Cyclosporins / Q000276:immunology / Q000378:metabolism* / Q000652:urine; D006801:Humans; D007166:Immunosuppressive Agents; D016030:Kidney Transplantation / Q000276:immunology; D007959:Lymphocyte Culture Test, Mixed; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008991:Monitoring, Physiologic
D003524:Cyclosporins; D007166:Immunosuppressive Agents