IN-VIVO EFFECTS OF A NEW IMMUNOSUPPRESSIVE SIGMA-LIGAND, SR-31747, ONMOUSE THYMUS

SR 31747 is a new sigma ligand which has immunosuppressive properties. The immunopharmacology of SR 31747 was investigated in vivo by studyi ng its effects on the thymuses of C3H mice. The action of SR 31747 was compared with the reference drugs cyclosporin-A and dexamethasone on the basis of several parameters which were: the thymus weight; the num ber of thymocytes per organ; the Percentages of mature CD4(+) or CD8() thymocytes and of immature CD4(+) CD8(+) thymocytes. SR 31747 slight ly but significantly decreased the thymus weight at the dose of 50 mg/ kg whereas the number of thymocytes per organ was significantly decrea sed from 6.25 mg/kg to the 50 mg/kg dose. It had rather no effect on t he percentages of immature and mature subsets. These data led to the c onclusion that the effects of SR 31747 on the thymuses of C3H mice wer e close to those obtained with cyclosporin-A and different from those obtained with dexamethasone.