| Pesticides are widely used in agriculture and forestry for their function of increasing yields by controlling diseases and pests effectively.However,pesticides also have toxic effects on non-target organisms.Long-term and short-term exposure to pesticides may induce general toxicity,neurotoxicity,reproductive toxicity and immunotoxicity.In this study,six common moderate and low toxic pesticides with different chemical compositions include Chlorpyrifos(CPF),Fenitrothion(FNT),Malathion(MLT),Paraquat(PQ),Fenvalerate(FEN),Toxaphene(Polychlorinated Camphene,PCC)were selected to study their immunotoxicity.The immunotoxity of experimental pesticides was first evaluated in this study via measuring the cell viability of splenocytes,T lymphocytes and B lymphocytes as well as the level of interleukin-2 secreted by T lymphocytes.Then the level of reactive oxygen species,enzymatic and nonenzymatic antioxidants in splenocytes were assayed to explore the related mechanisms preliminarily.The main results were as follows:(1)Study on the effects of different pesticides on the viability of splenocytes.The murine splenocytes viability was measured by MTT assay when exposed to CPF,FNT,MLT,PQ,FEN,PCC at different concentration(10-6 M,10-5 M,10'4 M).It was found that all the experimental pesticides inhibited the proliferation of splenocytes in a dose-related manner.And such inhibition was significant at the concerntion of 10-4 M.The orders of proliferative toxicity from strong to weak were from PCC,MLT,CPF,PQ and FNT to FEN.(2)Study on the effects of different pesticides on spleen lymphocyte subsets.T lymphocytes were stimulated by mitogens Concanavalin A and B lymphocytes were treated by Lipopolysaccharide.The splenocytes were co-cultured with Concanavalin A or Lipopolysaccharide and pesticides at 10-4 M.It was found that FNT,MLT,FEN and PCC selectively inhibited the proliferation of T lymphocytes but CPF selectively inhibited the proliferation of B lymphocytes.However PQ inhibited both.The orders of proliferative toxicity of T lymphocytes from strong to weak were from PCC,MLT,FNT and FEN to PQ,and the orders of proliferative toxicity of B lymphocytes from strong to weak were from PQ to CPF.(3)Study on the effects of different pesticides on the function of splenocytes.The splenocytes were treated with experimental pesticides(10'5 M,10-4 M).The levels of interleukin-2 secreted by spleen T lymphocytes were measured by enzyme-linked immunosorbent assay.It was shown that all the experimental pesticides inhibit the function of spleen T lymphocytes to secret interleukin-2 in a dose-related manner,and significantly inhibited the function at 10-4 M.The orders of inhibition of T lymphocytes' function from strong to weak were from PQ,FEN,PCC,CPF and FNT to MLT.(4)Preliminar study on the mechanisms of pesticides inducing immunotoxicity in splenocytes.The level of ROS and nonenzymatic antioxidants Glutataione(GSH)as well as the activity of enzymatic antioxidants Glutathione Peroxidase(GSH-Px),Glutathione Reductase(GR),Glutathione S-transferase(GST)and Superoxide Dismutase(SOD)were measured to study the relationship between pesticides'toxicity and oxidative stress induced by them.The results showed that except CPF,the other experimental pesticides caused excessive reactive oxygen species production in the cells;all the experimental pesticides decreased the level of GSH;except FEN,the other experimental pesticides significantly decreased the axtivity of GSH-Px;MLT,PCC and CPF significantly decreased the axtivity of GR;except PQ,the other experimental pesticides significantly decreased the axtivity of GST;except PQ and CPF,the other experimental pesticides significantly decreased the axtivity of SOD.These results indicated that the immunotoxicity of six pesticides is closely related to oxidative stress induced by them.The above results showed that pesticides CPF,FNT,MLT,PQ,FEN and PCC have the immunotoxicity in splenocytes,and its immunotoxicity is closely related to oxidative stress induced by them. |
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