Objective Benzothiazole derivative BD960 has immunosuppressive activity after cell -based assays for high-throughput screening.The paper aimed to investigate the involved mechanism of BD960 on T cell proliferation. Methods Human peripheral blood T-lymphocytes were isolated and purified by the immunomagnetic microbeads.Then the T cells were activated by anti-CD3/anti-CD28 mAbs or alloantigen.The effect of BD960 on activa-ted T cell proliferation, the cytotoxic effect BD960 on resting T cells and the expression of activated T cells marker CD25 were measured by flow cytometer.Cytokine levels, including IL-2, IL-4, IL-6, IL-10, IL-17A and IFN-γ, were determined by ELISA. Results BD960 significantly inhibited the proliferation of T cells stimulated by anti-CD3/anti-CD28 mAb or alloantigen in a dose-dependent manner.The IC50 value is (2.3 ±0.3)μmol/L or (2.5 ±0.3)μmol/L, respectively.Moreover, BD960 had no obvious cytotoxic effects on rest-ing T cells and peripheral blood mononuclear cells, even at a high concentration ( up to 100μmol/L) .The ratio of CD25 expression on T cell was 69.7%after stimulated by Anti-CD3/CD28 mAbs with 72 h, the concentration (0.625、2.5、10)μmol/L of BD960 also had no potent effects on the ratio, but 0.1μmol/L FK506 could inhibit CD25 expression as low as 9.4%.The G0/G1 phase of activated T cells was 58.5%after stimulated by BD960 with 96 h.BD960 could induce cell cycle arrest at the G0/G1 phase in activated T cells with the increase of concentration and RAPA in the concentration of 0.1 μmol/L was 91.5%.In addition, BD960 (0.625、2.5、10)μmol/L could inhibit the secretion of IFN-γ, IL-6 and IL-17 in activated T cells with the increase of concentration, without any effects on the secretion of IL-2, IL-4 and IL-10. Conclusion BD960 not only exerts the inhibition on the late stage of T cell activation of cell proliferation but also inhibits the secretion of inflammatory cytokines, such as IL-6, IL-17 and IFN-γ, while the mechanism of BD960 on T cell proliferation was not the same as FK506.As a result, BD960 has the potential to be the lead compound to develop a new immunosuppressant.

Obej ctive Abnormal proliferation of T cells plays an important role in the development of autoimmune diseases. The article aimed to study the inhibitory effect of small molecule compound BD691 on T cell proliferation and its mechanism. Methods Human peripheral blood T-lymphocytes were isolated and purified by the immunomagnetic microbeads,then T cells were ac-tivated with anti-CD3/CD28 mAbs or alloantigen.The inhibitory effect of BD691 on activated T cell proliferation, the cytotoxic effect BD891 on resting T cells and the expression of activated T cells marker CD25 were measured by flow cytometry.Furthermore, ELISA was used to detect the secretion of cytokines associated with T cell differentiation. Results BD691 significantly inhibited the prolif-eration of T cells being stimulated by anti-CD3/CD28 mAb or alloantigen in a dose-dependent manner, and IC50 values are (8.5 ± 1.5)μmol/L and (7.2 ±1.3)μmol/L, respectively.However, BD691 had no obvious cytotoxic effects on resting T cells and periph-eral blood mononuclear cells, even at a high concentration ( up to 100μmol/L) .In T cells which were not activated by anti-CD3/CD28 mAb, the percentage of CD25+T cells is only 1.6%of the total cells, while the number increased to 68% after activating treatment.Mean-while, in T cells which were activated by 0, 3.3, 10, 30μmol/L BD691, no obvious change of CD25 expression were observed, while immunosuppressant FK506 (0.1μmol/L) significantly decreased the expression of CD25 +T cells (14.9%).In unactivated T cells, 95.6%cells were at G0/G1 phase, while after activation, the percentage of cells at G0/G1 phase reduced to 57.7%.In addition, BD691 inhibited the secretion of IFN-γ, IL-6 and IL-17 in activated T cells, but had no effects on the secretion of IL-2, IL-4 and IL-10. Co nclusion BD691 exerts no effects on T cell activation, but it inhibits T cell proliferation by inducing T cell cycling arrest at G0/G1 phase.Moreover, BD691 inhibits the secretion of key cytokines (such as IFN-γ, IL-6, IL-17) closely related to the differ-entiation of Th1 and Th17 cells.The results suggest that BD 691 is a potential lead compound to develop a new immunosuppressant for the inhibition of abnormal proliferation and differentiation of T cells.