title: Coexpression of CD4 and CD8alpha on rat T-cells in whole blood: a sensitive marker for monitoring T-cell immunosuppressive drugs.
abstract: The aim of this study was to develop a new quantitative method for measuring in vitro the effects of T-cell immunosuppressive drugs by flow cytometry. Rat whole blood samples were stimulated with the T-cell mitogen succinylated concanavalin A in the presence or absence of different drugs. After 3 days, the expression of CD25 and CD8alpha in mitogen-stimulated CD4(+) cells increased 10- to 20-fold as measured by flow cytometry. Drug efficacy and potency was calculated based on dose-response curves of the drug-mediated decrease in CD4(+)/CD8alpha(+)/CD25(+) cells. The expression of CD8alpha in mitogen-stimulated CD4(+) cells was blocked completely by calcineurin inhibitors (cyclosporine A and FK-506), and partially by rapamycin and SDZ-RAD. The IC(50) (50% inhibitory concentration) values obtained were (mean+/-S.E.): 99.5+/-16.6 nM for cyclosporine A, 10.4+/-1.3 nM for FK-506, 1.8+/-0.7 nM for rapamycin, and 6.4+/-1.1 nM for SDZ-RAD. Our results show, for the first time, that CD8alpha, used as an activation antigen, is a sensitive marker for monitoring T-cell immunosuppression.
authors.affiliation: Department of Transplantation, Preclinical Research, Building 386/628, Novartis Pharma AG, Lichstrasse 35, CH-4002 Basel, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Diaz-Romero
authors.forename: G
authors.initials: G
authors.lastname: Vogt
authors.forename: G
authors.initials: G
authors.lastname: Weckbecker
mesh_terms: D000818:Animals; D015415:Biomarkers; D015704:CD4 Antigens / Q000096:biosynthesis*; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects* / Q000276:immunology; D016827:CD8 Antigens / Q000096:biosynthesis*; D003208:Concanavalin A / Q000494:pharmacology; D016572:Cyclosporine / Q000494:pharmacology; D000068338:Everolimus; D000068876:Fingolimod Hydrochloride; D005434:Flow Cytometry / Q000379:methods; D006146:Guanidines / Q000494:pharmacology; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D008934:Mitogens / Q000494:pharmacology; D011409:Propylene Glycols / Q000494:pharmacology; D051381:Rats; D011917:Rats, Inbred Lew; D020123:Sirolimus / Q000031:analogs & derivatives / Q000494:pharmacology; D013110:Sphingosine / Q000031:analogs & derivatives; D016559:Tacrolimus / Q000494:pharmacology
chemical_list: D015415:Biomarkers; D015704:CD4 Antigens; D016827:CD8 Antigens; D006146:Guanidines; D007166:Immunosuppressive Agents; D008934:Mitogens; D011409:Propylene Glycols; D003208:Concanavalin A; D016572:Cyclosporine; D000068338:Everolimus; D000068876:Fingolimod Hydrochloride; D013110:Sphingosine; C037258:gusperimus; D020123:Sirolimus; D016559:Tacrolimus