Objective: To study the effects of (E)-2-(4-bromophenyl)-1-(3, 4-dihydroxyphenyl) ethanone oxime (BDEO) on the proliferation and activation of the mice' s splenic lymphocytes and the peripheral blood lymphocytes induced by Concanavalin A (Con A) in vitro and in vivo, and its molecular mechanism.
Methods: During the lymphocyte proliferation and activation induced by Con A in vitro, MTT and cell counting were used to detect the transformation rates and survival rates of lymphocytes, and ELISA was used to measure the activity of caspase-9; moreover, the levels of Bax, Bcl-2 and caspase-3 were determined by Western blot, in order to observe the effects of BDEO on cell proliferation and activation. The effects of administration of Con A [15 mg/(kg x d)] and BDEO [(3, 6 mg/(kg x d)] by intraperitoneal injection on transformation rates of spleen cells and peripheral blood lymphocyte, as well as phagocytosis rate of peritoneal macrophages in mice were also observed in vivo.
Results: 0.3-1 micromol/L BDEO significantly inhibited the transformation rates and growth of mice lymphocyte (P < 0.05). The activity of caspase-9 and the levels of mitochondrial pro-apoptotic protein Bax and Bak gradually increased, then decreased as the BDEO continually accumulated. Anti-apoptotic protein Bcl-2 as well as mitochondrial Cyt C levels first decreased then increased gradually, and cytoplasmic Cyt C, cleaved caspase-9 and cleaved caspase-3 levels showed firstly a increase, then decrease gradually. Additionally, administration of BDEO by intraperitoneal injection significantly inhibited proliferation of spleen lymphocytes and peripheral blood lymphocyte, as well as phagocytosis of peritoneal macrophagesin in mice.
Conclusion: BDEO might regulate the proliferation and activation of lymphocytes through activation of caspase-3 mainly via a mitochondrial intrinsic pathway; the inhibiting effect on the proliferation and transformation rate of lymphocytes was significant when the concentration of BDEO was relatively low; as the concentration accumulated increasingly, the inhibiting effect reduced. The results indicated that BDEO has immunosuppressive activity.