[Changes of CD4+CD25+ T cells in the spleen of mice infected with Toxoplasma gondii].
OBJECTIVE
To observe the changes of CD4+CD25+ regulatory T cells in the spleen of mice infected with T.gondii.


METHODS
Twenty-eight female C57BL/6 mice were randomly divided into four groups. Three groups of mice were inoculated intraperitoneally with 10(4) tachyzoites in 200 microl sterile PBS. At 2, 4 and 6 days post-infection, the spleens were removed. The expression level of Foxp3 mRNA in splenic CD4+ T cells was quantitated by real-time PCR. The percentage of CD4+CD25+ regulatory T cells in CD4+ T cells was determined by flow cytometry, and the absolute numbers of splenic CD4+CD25 - regulatory T cells and CD4+ T cells were assessed. The fourth group was injected intraperitoneally with 200 microl sterile PBS as control.


RESULTS
The relative mRNA level of Foxp3 in splenic CD4+ T cells at day 4 (1.89+/-0.23) and day 6 (1.79+/-0.24) post-infection was significantly higher than control (1.00+/-0.12) (P< 0.01). After an initial up-regulation at 2 days post-infection (15.07%+/-2.73%) (P<0.05), the proportion of CD4+CD25+ regulatory T cells in CD4+ T cells at day 4 (24.29%+/-3.19%) and day 6 (19.80%+/-2.66%) post-infection was significantly higher than control (11.58%+/-2.04%) (P<0.01). At day 6 post-infection, both the percentage of splenic CD4+ T cells in splenocytes(5.49%+/-l.71%) and absolute number of CD4+ T cells (1.71+/-0.44)x106 greatly decreased(P<0.01).


CONCLUSIONS
The proportion of splenic CD4+CD25+ regulatory T cells in CD4+ T cells has been up-regulated following T. gondii infection, which is mainly due to a great reduction of CD4+ T cells in the spleen.
Ge
Yi-yue
YY
Department of Pathogenic Biology, Nanjing Medical University, Nanjing 210029 China.
Zhang
Gai
G
Wu
Jiang-ping
JP
Wang
Yong
Y
Hu
Wei
W
Tan
Ming-juan
MJ
D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism / Q000469:parasitology; D005260:Female; D005434:Flow Cytometry; D051858:Forkhead Transcription Factors / Q000235:genetics; D015870:Gene Expression; D006790:Host-Parasite Interactions; D007108:Immune Tolerance; D053645:Interleukin-2 Receptor alpha Subunit / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011897:Random Allocation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013154:Spleen / Q000166:cytology / Q000469:parasitology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology* / Q000378:metabolism / Q000469:parasitology; D014122:Toxoplasma / Q000502:physiology*; D014124:Toxoplasmosis, Animal / Q000276:immunology* / Q000469:parasitology*
D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; D053645:Interleukin-2 Receptor alpha Subunit; D012333:RNA, Messenger