Immunosuppressive mode of action of deoxyspergualin and deoxymethylspergualin

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1)ln vitro modet(human)The effect of Deoxymethylspergualin (MeDSG) on 'in vitro' human lymphoc e response was assessed in comparison with ciclosporin (CYA) and FK506. Peripheral blood mononuclear (PBMN) cells from normal human volunteers were used for assays of mixed lymphocyte reaction (MLR). cell mediated 13, mpholys is (CML) and blastogenesis by PHA, IL2 and OKT3. MEDSG suppressed only allogeneic stimulation (MI. R and CML) and IL2 induced blastogenesis but not PHA or OKT3 induced blastogenesis, although the other immunosuppressive agents showed some suppressive effects for all assays. Kinetic study of MLR showed that the suppressive activity did not decrease even when MEDSG was added at day 3 or day 4. FK506 and CYA, however, showed a decline of suppressive activity when added at a later phase of MLR. MeDSG also acted on the comparatively early phase of cytotoxic effecter cell generation in allogerieic stimulation.2)ln vivo mociel (rat)In the present study, the survival of heart al … More lograft in rats after a short course of DSG treatment and the mechanism underlying DSG-induced heart allograft survival, in the early phase, were studied. Male LEW rats were used as recipients& Male ACI and Wister rats were used as donors and and the third party donors, respectively. Survival of ACI lieart grafts in LEW recipients treated with a short course of DSG, beginning from day 4 of grafting, were markedly prolonged, with a mean survival time of 16.6+5.8 days and 29.8+3.0 days at the dose of 2.5mg/kg/day and 5. Omg/kg/day, respectively.On day 20 postgrafting. the mechanism of inducing alograft survival after DSG-treatment was further analyzed by testing the ability of spleen cells or serum in several assay systems. Spleen cells from DSG-treated rat with surviving heart allograft showed no proliferative response against donor strain stimulator cells compared with the control. The cytotoxic activity of spleen cells from DSG-treated rat with surviving heart allograft was lower than the spleen cells from rat with rejected heart allograft towards donor strain target cells. Adding various concentrations o-f spleen cells or serum from DSG treated LEW rat with surviving ACI heart allograft to MLR revealed a strong suppression, in a cell-dose-dependent manner and serum-dose-dependent manner, both in donor strain and third party MLR.Moreover. transfer of 2.0x10^8 spleen cells or 2 ml senn from DSG treated LEW rat with siuwiving ACI heart allograft to sublethal irradiated grafted host did not prolong survival, both in ACI heart grafts and third party Wister heart grafits. These results suggest that proliferative response and cytitoxic activity are decreased and suppressor cells and humoral factorps')are induced, by treatment with DSG in the early phase of rats with surviving allgraft. Less