Increased Prevalence of Activated CD83+CD4+ T Cells with Immune Thrombocytopenia

Objective: ITP(immune thrombocytopenia)is an autoimmune disease characterized by platelet decrease and risk of bleeding increase. Usually CD83 is mature DCs'(dendritic cells ) selective marker, but also found in other kinds of cells including thymic epithelial cells an T-cells, especially regulatory T cells and B cells. CD83 and sCD83 may play an important role in autoimmune. The aim of the research is to explore the CD83 expression in CD4+ T-cells subset and analysis the relationship between CD83+ and ITP patients' status and prognosis.

Methods: 76 ITP cases were selected, who diagnosed by international experts' consensus in 2009, excluding other autoimmune diseases. The CD83+CD4+T cells expression tested in different ITP group and normal , and done correlation analysis with clinical indexes, such as gender, age, progress and platelet count. PBMCs of ITP and normal group cultured in vitro. anti-CD3/28, anti-CD3/28+TGF-β, anti-CD3/28+TGF-β+CD83 monoclonal antibody taken into culture system respectively, RT-PCR was used to test CD83 expression in PBMCs and FCM was used to analyze the relationship between CD83 and CD4+CD25-、CD4+CD25+、CD4+CD25+FOXp3+Treg. The concentration of sCD83 in plasma are tested, then made the correlation analysis between sCD83 and platelet count.

Results: the FCM showed the ratio of CD83+CD4+T cells as follows: initial treatment group (n=19, M±S:6.47±0.55%), active stage group (n=23, M±S:3.93±0.46%), remission group (n=25, M±S:2.97±0.26%), normal control group (n=23, M±S:2.60%±0.33). Initial treatment group and active stage group were higher than remission group and normal control group significantly. There is statistical significance (P=0.001). ITP patients' CD83+CD4+T cells number was negative correlation with staging of disease(r=-0.494, P=0.002). CD83 was rarely expressed on resting CD4 +T cells in ITP (n=4), whereas the percentages of CD83-positive cells in the total CD4 + T cells were significantly upregulated at 24h (2.49±0.31%), remarkable increasing at 48h(5.48±0.48%), however decreased at 72h(1.97±0.32%). In all groups(n=4), CD4+CD25- cells expressed low CD83 (3.17±0.32%), CD4+CD25+ cells higher (15.97±0.76%), CD4+CD25+FOXp3+Treg cells highest (26.87±1.31%).Anti-CD83 decreased the expression of CD83. TGF-β increased the expression of CD83. Compared with normal group, ITP groups express more CD83 mRNA. Normal plasma (n = 24) had a mean sCD83 concentration (M±S) of 42.30±9.17pg/ml and similar levels were observed in initial treatment group (n =21, mean =151.03 ± 21.01pg/ml), active stage group (n=23, mean =117.67±11.9pg/ml), remission group (n=25, mean =98.52±14.23pg/ml). In accord with CD83+CD4+T cells, ITP groups' sCD83 in peripheral plasma increased, however negative correlation with platelet count(r=-0.438,p=0.007), no correlation with gender and age.

Conclusions: CD83+CD4+T cells was significantly negative correlation with ITP stage. Platelet count was significantly negative correlation with sCD83. As the release of illness, CD83+CD4+T cells expression and sCD83 level down significantly. CD83 expression increasing in Treg cells may be connected with immune suppression function disorder, at the same time sCD83 may monitor the status of ITP patients in the future.