Study On The Lymphocyte Immunologic Function Effects Of Microcystins From Cyanobacteria Bloom In Shanzi Reservoir And Its Mechanism In Mice.

Objective: Study on the lymphocyte immunologic function effects of microcystins from cyanobacteria bloom in Shanzi reservoir and its mechanism in mice. Method:1.The immunologic inhibition on lymphocytes of mice induced by microcystins from cyanobacteria bloom in Shanzi reservoirMice spleen lymphocytes were suspended at a density of 3.0×106cells/ml in RPMI 1640 medium supplemented with 10% fetalcalf serum and were distributed in fat-bottomed 96-well microtiter plates for six well, Mice spleen lymphocytes were treated with MC-LR at the dose of 0,1,3,5,10μg MC-LR /ml for 72h(Our previous work had indicated the presence of microcystin in cyanobacteria bloom collected from shanzi and showed that the main toxic component of cyanobacteria bloom extract is MC-LR) and tested for lymphoproliferation; Mice NK cells were also suspended at a density of 3.0×106cells/ml in RPMI 1640 medium supplemented with 10% fetalcalf serum and were distributed in fat-bottomed 96-well microtiter plates for six well, then NK cells were treated with MC-LR at the dose of 0,1,3,5,10μg MC-LR /ml for 24,48,72h and tested for cell activity.2.The study on the mechanism of effects on lymphocytes of mice induced by microcystins from cyanobacteria bloom in Shanzi reservoirMice spleen lymphocytes were suspended at a density of 3.0×106cells/ml in RPMI 1640 medium supplemented with 10% fetalcalf serum and were distributed in fat-bottomed 48-well microtiter plates for six well,Mice spleen lymphocytes were treated with MC-LR at the dose of 0,1,3,5,10μg MC-LR /ml for 24h and tested for the production of IL-2,the abundance of IL-2mRNA and the lymphocyte apoptosis by fluorescene microscopy and monochromicflow cytometry(FCM).Result:1.The immunologic inhibition on lymphocytes of mice induced by microcystins from cyanobacteria bloom in Shanzi reservoir1.1 The proliferation of T,B lymphocytes was decreased at the dose of 1,3,5,10μg MC-LR /ml in a obvious dose-effect manner compared with the control (P<0.05).1.2 Mice NK cells activity was decreased markedly by MC-LR at the dose of 5,10μg MC-LR /ml after 24h in comparison to the control(P<0.05); MC-LR at the dose of1,3,5,10μg /ml markedly decreased the mice NK cells activity after 48h and 72h in comparison to the control(P<0.05),the cells activity reduced in a dose and time-effect manner.2.The study on the mechanism of effects on lymphocytes of mice induced by microcystins from cyanobacteria bloom in Shanzi reservoir2.1 There was a diphasical effect on lymphocyte IL-2 by microcystins from cyanobacteria bloom in Shanzi reservoir, MC-LR at the dose of1,3μg MC-LR /ml markedly increased the production of IL-2 and abundance of IL-2mRNA in mice,only MC-LR at the dose of 1μgMC-LR/ml had a statistical significance in comparison to the control(P<0.05);but the production of IL-2 and abundance of IL-2mRNA were decreased markedly by the dose of 5,10μg MC-LR /ml compared with the control (P<0.05).2.2 MC-LR at the dose of 5,10μg MC-LR /ml markedly diminuted the lymphocytic cubic and showed that the flavovirens cell nucleus were crescent and fragmental,but the bouncaries of lymphocytic cell nucleus were regular and well-arranged ,the chromatins were dyed in flavovirens and homogeneous were distributed, and there were no conspicuous conglomerate in the cell nucleus in the control; there was a obvious"deuto-G1 capylus"and the apoptosis rate was increased obviously at the dose of 10μg MC-LR /ml by monochromicflow cytometry(FCM) in comparison to the control(P<0.05).Conclusion:1.Microcystins from cyanobacteria bloom in Shanzi reservoir could decrease the proliferation of T,B lymphocyte and reduce the NK cells activity significantly in vitro as compared to the control, so microcystins from cyanobacteria bloom in Shanzi reservoir could markedly inhibit the lymphocyte immunologic function in mice in a dose and time-effect manner.2.The dose of 5,10μg MC-LR /ml microcystins from cyanobacteria bloom in Shanzi reservoir could obviously inhibit the abundance of IL-2mRNA and decrease the production of lymphocyte IL-2 in mice in vitro,maybe it is one of the mechanisms of reducing the lymphocyte immunologic function in mice.3. The dose of 10μg MC-LR /ml microcystins from cyanobacteria bloom in Shanzi reservoir could obviously increase the lymphocyte apoptosis rate in mice in vitro, maybe it is another mechanism that the lymphocyte immunologic function could be reduced by apoptosis induced by microcystins from cyanobacteria bloom in Shanzi reservoir.4. The lymphocyte IL-2 is more sensitive to the low dose of microcystin(1μg MC-LR/ml),it would be used to predict the immunotoxicity of microcystin.