Research On The Immunosuppression And Mechanism Of 3-Chloro-1,2-Propanediol Palmitate Esters On Mice T Lymphocytes

3-chloro-1,2-propanediol(3-MCPD)fatty acid esters,are mainly produced in oil refining process.Recently,the security of 3-MCPD esters has raised public concern.To date,the toxicological studies of 3-MCPD esters have been mainly focused on the kidneys and testis,however,its toxicology and exposure assessment data are still limited,especially the effects on immune system.In the present study,we chose three 3-MCPD palmitate esters(1-palmitoyl-3-chloropropanediol(1-pal),2-palmitoyl-3-chloropropanediol(2-pal)and 1,2-dipalmitoyl-3-chloropropanedio(dipal))as probe compounds to investigate immunosuppressive effect and mechanism of 3-MCPD fatty acid esters on mice T lymphocyte in vitro and vivo.First,the inhibiting effect of 3-MCPD palmitate esters on T splenocyte and B splenocyte proliferation was determined using MTT method.The results showed 1-pal and 2-pal but not dipal significantly inhibited ConA-stimulated T splenocyte proliferation.Only 2-pal had a notable suppression on LPS-stimulated B splenocyte proliferation,so the next study was continued with focus on T lymphocyte.Then the effects of3-MCPD palmitate esters on T lymphocyte cell cycle progression were investigated using flow cytometry analysis.The data showed that 1-pal and2-pal could inhibit T lymphocyte proliferation through suppressing cells entrying into the S phase and G2/M phase.To further investigate the mechanism by which 3-MCPD monopalmitates affected the proliferation of T lymphocyte,the effects on MAPK signal pathways were examined using Western blot analysis.The results revealed that 1-pal significantly inhibited the JNK,p38 signal pathways,whereas 2-pal had no significant effect.Also,the effects of 3-MCPD palmitate esters on the differentiation of T lymphocyte were determined using flow cytometry analysis,indicating that 3-MCPD monopalmitates significantly reduced CD4~+T lymphocyte population and the ratioof CD4~+/CD8~+.Moreover,3-MCPD monopalmitates were found to significantly suppress the secretion of Th1and Th2 cytokines using ELISA.Both 1-pal and 2-pal significantly inhibited the NF-?B signal pathway,which was supported by Western blot and immunofluorescence data.For in vivo study,the immunosuppression of 1-pal on T lymphocyte was investigated using DNFB-induced DTH reaction.The ear thickness difference between the left and right ear was evaluated using an electronic vernier caliper.Moreover,the IFN-?in serum was analyzed using ELISA and histological analysis,which was performed on the left ears.It turned out that 1-pal significantly inhibited the DNFB-induced ear swelling and the expression of IFN-?in serum.Together,these data indicated that 1-pal had the immunosuppressive effect on T lymphocyte in vivo.Taking together,3-MCPD monopalmitates had immunosuppressive effects on mice T lymphocytes both in vitro and vivo,which was mediated by MAPK and NF-?B pathways.Different substitution location and number of palmitic acid might alter the toxicity of 3-MCPD esters.These results may provide theoretical basis for safety assessment of 3-MCPD esters.