Esculentoside A (EsA), a saponin isolated from the root of Phytolacca esculenta, has been reported to exert anti-inflammatory effects in several animal models of acute and chronic inflammation by inhibiting the production and activity of pro-inflammatory cytokines in macrophages and epithelial cells. However, little is known about its modulation on T cells. In the present study, we further investigated its potential in treatment of autoimmune disease and its modulation on T cells, using an experimental autoimmune model established through immunizing mice with Campylobacterjejuni strain CJ-S(131) in Freund's complete adjuvant. Our results demonstrated that EsA administration markedly alleviated the inflammatory injury in liver and kidney of model mice, decreased the anti-CD3/CD28-stimulated proliferation of splenocytes and lymph node cells, and reduced the percentage of CD3+, CD4+, and CD8+ lymphocytes in peripheral blood. Furthermore, we demonstrated that EsA induced apoptosis in ConA-activated thymocytes but not in non-activated thymocytes. Gene expression analysis revealed that EsA up-regulated the expression of a group of pro-apoptotic genes more profoundly in Con A-activated thymocytes than in non-activated thymocytes. EsA-affected pro-apoptotic genes included those involved in Fas induction, p53 activation, redox metabolism, calcium- and glucocorticoid-induced apoptosis signals, suggesting that EsA may modulate multiple apoptotic signal pathways in activated T cells. Taken together, our findings suggest that EsA may be useful for the treatment of autoimmune disease through modulation on T cell-mediated adaptive immunity.