Effects of 15-deoxyspergualin on proliferative responses and cytokine gene expression in vitro

15-deoxyspergualin (DSG)-treated BALB/c spleen cells showed increased spontaneous proliferation and increased alloreactive mixed lymphocyte reactions (MLRs) when a 3-h treatment was carried out. However, when spleen cells were treated with DSG for 5 days without washing out DSG, decreased spontaneous proliferation was observed, although alloreactive MLRs against C3H/He and C57BL/6 alloantigens were increased. In contrast, cyclosporin A (CsA) induced markedly decreased alloreactive MLRs. Decreased concanavalin A (Con A)- and pokeweed mitogen (PWM)-induced responses were observed in spleen cells treated with DSG for 3 h; whereas increased phytohemagglutinin (PHA)-induced responses were observed. On the other hand, increased Con A- and PHA-induced responses were observed in spleen cells treated with DSG for 2 days, whereas PWM-induced responses were decreased. CsA-treatment induced markedly decreased mitogen-induced responses. These results suggest that the immunosuppressive mechanism of DSG differs from that of CsA. Reverse transcriptase-polymerase chain reaction (RT-PCR) method showed that interleukin 1 beta (IL-1 beta), IL-2, IL-3, IL-4, IL-5, and leukemia inhibitory factor (LIF) mRNA expression in DSG-treated spleen cells were increased by Con A stimulation, thus indicating that DSG modulates cytokine gene expression and inducing immunosuppressive mechanisms different from CsA.