OCH-mediated shift of Th1 and Th2 cytokines by NKT cells in mice with aplastic anemia.

The immune-mediated destruction of bone marrow (BM) is the major cause of aplastic anemia (AA) in most patients. It has been shown that an imbalance of Th1 and Th2 cells is involved in immune-mediated destruction of BM in patients with AA. In the present study, we determined the role of NKT cells in regulating the balance of Th1 and Th2 cytokines. We found that the number of NKT cells from bone marrow mononuclear cells was lower in AA mice than normal mice. When treated with α-GalCer or its analog OCH, AA mice showed a significantly reduced capacity of NKT cell expansion. Furthermore, we found that the number of IFN-γ-producing NKT cells was higher in AA mice compared to normal counter-partners. However, OCH treatment inhibited IFN-γ production and enhanced IL-4 production by NKT cells in which we saw a balanced Th1- to Th2-type cytokines in AA mice. Interestingly, we observed that OCH treatment promoted hematopoietic cell growth, as indicated by increased colony counts in AA mice. Taken together, our results not only demonstrated a role of OCH in the maintenance of Th1/Th2 balance and recovery of hematopoietic cell growth, but also revealed a therapeutic potential of OCH in AA.

OCH ameliorates bone marrow failure in mice via downregulation of T-bet expression.

The aim of this study is to evaluate the immune mechanism of OCH in the treatment of AA (also named bone marrow failure, BMF) induced in mice. OCH at a dose of 400 µg/kg was injected intraperitoneally (I.P.) prior to the induction of BMF. Our study showed that the incidence of BMF was 100% in BMF group and 13% in OCH treatment group. Significant higher level of IL-4 and lower level of IFN-γ were observed in OCH group than that in BMF group (P < 0.05) as well as untreated group over BMF (P < 0.05). However, there was no significant difference between OCH and untreated group. Compared with untreated, the expression level of T-bet in OCH and BMF was all significantly higher. However, T-bet expression level was lower in OCH than in BMF. In addition, OCH treatment increased NKT cell fractions of bone marrow and the colonies of CFU-GM. In conclusion, treatment of OCH prior to the induction of BMF could prevent the incidence of BMF possibly through downregulating T-bet expression leading to the transition of immune response from Th1 to Th2, suggesting OCH might be a new therapeutic approach in the treatment of BMF or AA.

Comparison of rabbit antithymocyte globulin and Jurkat cell-reactive anti-T lymphocyte globulin as a first-line treatment for children with aplastic anemia.

The purpose of this study was to investigate the effects of rabbit antihuman thymocyte globulin (R-ATG) and Jurkat cell-reactive anti-T lymphocyte globulin (ATG-F) in the treatment of childhood aplastic anemia (AA) and compare their efficacy and side effects. A total of 53 children with AA were analyzed in the present study, including 32 cases of severe AA, 10 cases of very severe AA and 11 cases of transfusion-dependent nonsevere AA. While receiving immunosuppressive therapy (IST), 29 and 24 patients, all of whom received long-term oral supplement with cyclosporin A (CSA), androgen, and traditional Chinese medicines, were treated with R-ATG and ATG-F, respectively. If necessary, the patients were also given supportive care such as component transfusion and/or infection control. Absolute counts of peripheral blood lymphocyte at various time points were dynamically measured after ATG therapy. According to the International AA Treatment and Effect standards, we found that there were no statistically significant differences in the response rate (70.83% vs. 68.97%, p > 0.05) and the overall survive rate (83.33% vs. 82.76%, p > 0.05) between the ATG-F and R-ATG groups. In addition, no obvious differences were observed between these two groups in the response time, efficacy in severe AA and very severe AA, or the incidence rates of ATG-related adverse reactions. After ATG treatment, the extent of peripheral blood lymphocyte reduction and duration in peripheral blood were similar between the ATG-F and R-ATG groups. The results of this study showed that ATG-F and R-ATG had similar efficacy and adverse reactions in the first-line treatment of childhood AA, despite being derived from different immunogens.

Long term cultured HL-60 cells are intrinsically resistant to Ara-C through high CDA activity.

Cytarabine (araC) is a highly active antimetabolite against hematological malignancy while the agent shows limited activity for some patients despite maintenance or continued therapy with ara-C-containing regiments. In this study, we focused to elucidate the mechanism of intrinsic resistance to araC. The concentration of intracellular ara-CTP and incorporated ara-CTP were monitored in human leukemia cell line-HL-60 for different passages in parental with its variant HL-60R. The expression of mRNA for deoxycytidine kinase (dCK), cytidine deaminas (CDA), human equilibrative nucleoside transporter 1 (hENT1), and cytosolic 50-nucleotidase II (cN-II) were examined by Real-time PCR in HL-60 and HL-60R for different passages. And activities of two metabolizing enzymes for araC, dCK and CDA were further examined. The results showed that the concentration of intracellular ara-CTP was significantly reduced and the ara-U increased in HL-60 cells for 50 passages compared with the 5 passages, and associated with higher CDA activity. All the factors in HL-60R cells did not change by the incubation of ara-C. In conclusion, the long term cultured cells are intrinsically resistant to ara-C through high CDA activity, but not low DCK activity.

[Treatment of childhood aplastic anemia with antithymocyte globulin, management of side effects and long-term follow-up].

OBJECTIVE: To evaluate the efficacy of antithymocyte globulin (ATG) based immunosuppression therapy for childhood aplastic anemia, to reduce the adverse effects and to observe the long-term outcome. METHOD: Thirty-five children with aplastic anemia (AA) were enrolled in this study. Six of the cases had very severe AA (VSAA), 11 had severe AA (SAA)-I, 8 had SAA-II and 10 had moderate AA (MAA). All these patients were treated with ATG plus Cyclosporin A (CSA). The following measures were taken during the ATG therapy: infection of the patients had been controlled before ATG treatment. Comprehensive anti-allergic measures were implemented. Close attention was paid to the hemorrhage related with platelet reduction caused by ATG and severe infection of the patients. RESULT: Shortly after the ATG usage, all the patients had a significant decrease of absolute peripheral lymphoblast count by more than 60 percent. With a mean follow-up time of 28 months, the total effective rate was 77.14% (27/35), significant response rate was 57.14%(20/35). There was no significant difference among VSAA, SAA and MAA groups in the response rate. Adverse reactions included the following: (1) 48.6% (17/35) patients presented mild anaphylactoid reaction during the first day of ATG treatment; (2) 42.9%(15/35) cases presented serum sickness 5 - 11 days after the last dose of ATG with a mean duration of 3.6 days, all the patients were cured effectively with methylprednisolone; (3) 25.7% (9/35) patient's peripheral blood platelet count was reduced, might be caused by ATG, to below 10 × 10(9)/L, but no patient had severe hemorrhagic complication after platelet transfusion was performed; (4) 22.9%(8/35)of patients got infection within a month after ATG therapy, including 3 cases with clinical septicemia, all the 3 cases recovered after antibiotics treatment. There was no ATG treatment-related death in this series. CONCLUSION: ATG is a very effective therapy for children with SAA and MAA. Comprehensive measures are needed to prevent and handle the side effects to avoid treatment-related death. Long-term supportive therapy and proper follow up contribute to the favourable outcomes of the patients.

The benefit of ATG in immunosuppressive therapy of children with moderate aplastic anemia.

BACKGROUND: Previous studies specifically focused on the immunosuppressive therapy (IST) of children with moderate aplastic anemia (MAA) are rare. The aim of this study was to evaluate the advantage of using antithymocyte globulin (ATG) in the IST and its outcome of children with MAA. METHODS: Forty-two children diagnosed with moderate aplastic anemia from 1993 to 2006 were retrospectively reviewed. Eighteen patients treated with ATG, cyclosporin A (CSA), and androgen are defined as the ATG group, the other 24 patients treated with CSA and androgen are defined as the non-ATG group. Survival and hematological response of the two groups were studied. RESULTS: Response rate and transfusion-independent survival of the ATG group were both significantly higher than those of the non-ATG group (83.33 vs. 41.7%, p = .006; and 83.33 vs. 50%, p = .043, respectively). Compared with non-ATG group, fewer patients in ATG group progress to severe aplastic anemia (p = .03). CONCLUSION: Immunosuppressive therapy including ATG benefits children with moderate aplastic anemia.