Benzo(a)pyrene Increases The Percentage Of Regulatory T Cells In The Spleen

Objective:Benzo(a)pyrene is a common pollutant in air and food.It is one of the public concerns that seriously endangers human health.Many studies indicate that benzo(a)pyrene not only has carcinogenicity but also immunotoxicity,which is mainly manifested in inhibition of immune function,but its mechanism is still not clear.Method:In this experiment,we used female BALB/c mice as an experimental animal model.Mice were divided into four groups,three experimental groups and one control group.Experimental group mice were given three different dose of BaP(0.1,1,10mg/kg)according to the body weight of mice.Mice were exposed to BaP by gavage,once a day,continuously for ten days.The control group mice were received only corn oil by the same manner.Eleventh days after exposure,body weight of mice was weighed.Spleens and kidney were removed and weighed,and the number of splenocytes,apoptosis and the percentage of Treg among CD4+T cells,percentage of DC in the spleen were measured by flow cytometry.We measured serum levels of blood urea nitrogen and activity of glutamic oxalacetic transaminase.Also,we determinated serum level of IgE and IgG1.The concentrations of IgE and IgG1 level in serum were measured by ELISA.Results:Our results show,3 doses of BaP significantly reduced the weight of the spleen,weight of kidney and reduced the number of immune cells in the spleen,in addition,BaP significantly increased the rate of late apoptosis of spleen cells,and increased the percentage of Tregs among CD4+T cells compared with control group.Our results show that BaP did not affect the IgGl and IgE level in the serum the content of BUN in the serum and the activity of GOT in serum of mice.Conclusions:Our results suggest that BaP has a direct toxic effect on immune cells.It increases apoptosis rate of spleen cells,increases Treg in CD4+T cells.It showed that BaP had no effect on the function of the kidney and the function of the liver,even it significantly reduces their weight.Our results provide a new basis for further understanding and prevention of the health effects of BaP.