[Study on expression of Treg cells in attenuated Schistosoma japonicum cercariae immunized BALB/c mice]

To study the expression differences of CD4+CD25+Foxp3+Treg cells between the attenuated cercariae immunized mice and the normal infected mice and discuss the immune protection mechanisms of the mice immunized with attenuated cercariae.

Forty female BALB/c mice were divided into 2 groups, group A, the attenuated cercariae immunized group (16 mices) and the group B, the normal cercariae infected group (16 mices), and the last 8 ones served as the blank control. The spleen cells and the ratios of PBMC's CD4+CD25+Foxp3+/CD4+CD25+T cells were compared between the attenuated cercariae immunized mice and normal mice injected by FCM and the Foxp3 expression levels in spleens and livers were assayed by IHC. The transcription factor Foxp3 in the peripheral blood was detected by RT-PCR.

In group A and group B, CD4+CD25+Foxp3+/ CD4+CD25+T ratios in the PBMC 6 weeks post-infection were (14.15 +/- 2.62)% and (7.92 +/- 2.22)%, respectively (P < 0.05); the ratios in the spleen cells were (14.52 +/- 2.98)% and (8.18 +/- 2.84)%, respectively (P < 0.05); 8 weeks post-infection, the ratios in the PBMC were (15.92 +/- 2.98)% and (13.26 +/- 2.64)%, respectively, (P < 0.05); the ratios of the spleen cells were (16.42 +/- 2.46)% and (13.48 +/- 2.36)%, respectively (P < 0.05); 6 weeks post-infection, the Foxp3 expression levels in livers were "+" and "-", respectively, and those in the spleens were "++" and "+", respectively; 8 weeks post-infection, the Foxp3 expression levels in the livers were "++" and "-" respectively, and those in the spleens were "++" and "+", respectively.

The expression level of attenuated cercariae immunized group's CD4+CD25+Foxp3+Treg cells is higher than that in the control group during the late stages, suggesting that CD4+CD25+Foxp3+Treg in the attenuated cercariae immunized mice may play one of the important roles in its immune protection mechanisms.