Detection and Significance of CD4+CD25+CD127dim Regulatory T Cells in Individuals with Severe Aplastic Anemia

Effect of arsenic trioxide on the Tregs ratio and the levels of IFN-γ, IL-4, IL-17 and TGF-β1 in the peripheral blood of severe aplastic anemia patients

Previous studies have suggested that the anticancer agent, arsenic trioxide (ATO), could attenuate T cell mediated immunity by not only inhibiting the proliferative response of T cells but by also increasing the frequency of regulatory T cells (Tregs). Furthermore, ATO represents a reasonable salvage treatment in some patients with refractory severe aplastic anemia (SAA). The current study aimed to evaluate the function of ATO on the Tregs percentage and cytokines changes in the peripheral blood mononuclear cells (PBMCs) of SAA patients.PBMCs were collected from 20 newly diagnosed SAA patients in Henan Cancer Hospital and treated with different concentrations of ATO (0, 1, 2.5, and 5 μmol/L). Then we investigated the efficacy of ATO on Tregs ratio and the levels of interferon (IFN)-γ, interleukin (IL)-4, IL-17 and transforming growth factor (TGF)-β1 in the peripheral blood of SAA patients in vitro.The results showed that ATO significantly increased the proportion of Tregs (P < .001) at 2.5 and 5 μmol/L concentrations, and the proportion of Tregs was increased with increasing ATO concentration (r = 0.524). At 1 (P = .03), 2.5 (P < .001) and 5 μmol/L (P < .001), ATO significantly up-regulated the expression levels of Foxp3 mRNA, which was positively and linearly correlated with the increase of Tregs cell-frequency (r = 0.52, 95%CI, 0.37-0.67). In addition, ATO significantly reduced the levels of IFN-γ (at 1, 2.5 and 5 μmol/L, P < .001), IL-4 (at 2.5 μmol/L, P = .009; at 5 μmol/L, P < .001), and IL-17 (at 2.5, P = .016; at 5 μmol/L, P < .001). ATO significantly reduced the levels of TGF-β1 at 5 μmol/L (P = .03), but showed no significant effects at 1 and 2.5 μmol/L (P > .05).ATO could mediate the immune regulation, which might contribute to improve hematopoietic recovery in SAA patients.

T-lymphocyte subsets and Th1/Th2 cytokines in convalescent patients with Epstein-Barr virus-associated aplastic anemia

Objective: The aim of this study was to analyze T-lymphocyte subsets and Th1/Th2 cytokines in convalescent patients with Epstein-Barr virus (EBV)-associated aplastic anemia (AA).Methods: Sixty AA patients were enrolled, who were in remission following immunosuppressive therapy, including 34 EBV-negative cases and 26 EBV-positive cases. Their complete blood count (CBC), T-lymphocyte subsets, Th1/Th2 cytokines were analyzed. The correlation between EBV-DNA and T-lymphocyte subsets was evaluated, as well as the relationship between EBV-DNA and Th1/Th2 cytokines. The presence of EBV-DNA in peripheral blood mononuclear cells (PBMCs) was also assessed in 60 normal controls.Results: EBV-DNA was detected in 26/60 (43.33%) patients and 21/60 (35.00%) controls. EBV-DNA copy number in AA patients was higher than in controls (Z = -2.138, P = 0.033). The percentage of CD3⁺CD4⁺ T-lymphocytes and the ratio of CD4⁺/CD8⁺ T-lymphocytes in the EBV-negative group were higher than in the EBV-positive group (P = 0.001 and 0.001, respectively). EBV was positively correlated with CD3⁺CD8⁺ T-lymphocyte percentages (Pearson R: 0.496, P = 0.009). Moreover, EBV was positively correlated with IL-10 and IFN-γ levels (Pearson R: 0.559, P = 0.002 and Pearson R: 0.621, P = 0.001, respectively).Conclusions: EBV-DNA copy number in AA patients was higher than in normal controls. Both AA and EBV infection may cause changes in the levels of T-lymphocyte subsets. We recommend monitoring the changes in the immune function and EBV infection simultaneously in AA patients, especially following immunosuppressive therapy.

Roles of regulatory T cells in the pathogenesis of pediatric aplastic anemia

The pathogenesis of aplastic anemia (AA) in children is not clear. This study was conducted to investigate the changes in the proportion and function of regulatory T cells (Tregs) in pediatric AA. The proportion of Tregs, mRNA levels of transcription factors, and concentrations of cytokines were measured by flow cytometry, reverse transcription-PCR, and enzyme-linked immunosorbent assay, respectively. Tregs were co-cultured with effector T cells (Teff) to evaluate the function of Tregs. The proportion of Tregs after immunosuppressive therapy (IST) in pediatric AA was monitored dynamically. Compared to the control, the proportions of Tregs in peripheral blood and bone marrow lymphocytes of the untreated AA group were lower (1.31% ± 0.73% vs. 3.16% ± 0.92%, 1.49% ± 0.81% vs. 3.06% ± 0.82%, respectively, p < 0.001). The mRNA levels of FOXP3 and STAT3 in the AA group were lower (p = 0.014; p < 0.001). However, the mRNA levels of T-BET did not significantly differ between groups. The concentration of interferon-γ and interleukin-17 in the AA group were higher (p = 0.004; p = 0.003), whereas the concentration of TGF-β decreased (p = 0.044). The immunosuppressive function of Tregs was impaired in the AA group. After IST, the proportion of Tregs was significantly lower than that in the control. The proportion of Tregs at the time of diagnosis in the nonresponsive group was lower than that in the responsive group, but the difference was not significant. Treg levels were significantly decreased and were functionally impaired at the time of diagnosis of pediatric AA. However, there was no significant change in Tregs at the resolution of AA.

Danazol increases T regulatory cells in patients with aplastic anemia

OBJECTIVES

Danazol is an attenuated androgen and is used in the treatment of aplastic anemia (AA) in resource constraint settings. We chose to study the role of CD4+ CD25^high CD127^low FoxP3+ T regulatory cells (T-regs) in the pathophysiology of AA and their response to treatment with Danazol alone or in combination with immunosuppressive treatment (IST).

METHODS

T-regs' percentages of 25 acquired idiopathic AA patients and 25 healthy controls who completed study protocol were analyzed by performing multicolor flowcytometry on peripheral blood samples.

RESULTS

More than one-third (36%) of AA patients in our study received Danazol as monotherapy, whereas less than a third (32%) each received standard doses of IST with equine Anti Thymocyte Globulin (ATG) and Cyclosporine combination, or Cyclosporine and Danazol combination, respectively. Results showed that all AA patients had a significantly lower percentage of T-regs at the time of diagnosis when compared to healthy controls (p < 0.0001), implicating their role in the pathophysiology. On treatment, all 25 patients showed a significant rise in the percentage of T-regs when compared to baseline (p < 0.0001).

DISCUSSION

The rise in T-regs' percentage was higher in patients treated with Danazol alone when compared to standard IST (ATG with Cyclosporine), or Cyclosporine with Danazol combinations (p = 0.585).

CONCLUSION

We conclude that Danazol also leads to increase in T-regs in acquired idiopathic AA.

Comparison of T lymphocyte subsets in aplastic anemia and hypoplastic myelodysplastic syndromes

AIMS

This study aims to compare the proportion of peripheral blood T lymphocyte subsets and related blood cell and bone marrow cytology indexes between patients with aplastic anemia (AA) and hypoplastic myelodysplastic syndrome (hypo-MDS), and investigate the clinical identification significance.

MATERIALS AND METHODS

A total of 41 patients with AA and 46 patients with hypo-MDS were collected, and the proportions of peripheral blood T lymphocyte subsets, CD3^-CD16/CD56⁺NK cells, CD3⁺CD57⁺T-LGL cells and CD19⁺B lymphocytes were detected by flow cytometry.

KEY FINDINGS

The CD4⁺/CD8⁺ ratio decreased in the AA and hypo-MDS groups, and the difference was statistically significant when compared with that in the control group (P<0.05). However, there was no significant difference between AA and hypo-MDS groups (P>0.05). The proportions of CD3^-CD16/CD56⁺NK cells and CD3⁺CD57⁺T-LGL cells in the hypo-MDS group were distinctly higher than those in the AA group (P<0.05). However, the proportion of CD19⁺B lymphocyte was obviously lower than that in the AA group (P<0.05). Furthermore, the proportions of reticulocytes, bone marrow progenitor cells and immature red blood cells in the hypo-MDS group were significantly more than those in the AA group (P<0.05), and the proportion of mature lymphocytes in the hypo-MDS group was distinctly lower than that in the AA group (P<0.05).

SIGNIFICANCE

Changes of T lymphocyte subsets and the proportions of large granular lymphocytes and B lymphocytes can be utilized as indexes in the differential diagnosis between AA and hypo-MDS.