[Natural history of moderate aplastic anemia in children and effects of immunosuppressive therapy].

OBJECTIVE In contrast to severe aplastic anemia (SAA), the appropriate management of patients with moderate aplastic anemia (MAA) is unclear. Recently, it was reported that when childhood MAA was treated with supportive care alone, 2/3 of patients progressed to SAA, and therefore patients with MAA should be treated with immunosuppressive (IS) therapy in time. The present study aimed to review the natural history, the rate of progression to SAA and outcome of children with MAA seen at our institution over the past 12 years and to explore the relationship between the effectiveness of IS therapy and the immune mediated pathological mechanism. METHODS Seventy-one MAA patients were included in this study. At the first stage, thirty-six children with MAA were given IS therapy (IS group, antithymocyte globulin, ATG or cyclosporin-A, CSA). The therapeutic effects were evaluated and compared with those of 35 children with MAA who received the treatment of supportive care alone (androgens, control group). At the second stage, the patients with MAA progressed to SAA were given combined immunosuppressive (CIS) therapy (CIS group, a combination of ATG, CSA and high-dose immunoglobulin). Peripheral blood lymphocyte subsets levels were measured with a flow cytometer. RESULTS At the first stage, in the IS group, the percentage of overall and complete responders was 83.3% and 69.4%, respectively, which was significantly higher than that of the control group (34.3% and 17.1%). Twenty-three patients with MAA progressed to SAA. In the control group, 18 patients with MAA progressed to SAA. In the IS group, five patients with MAA progressed to SAA. The 17 patients with MAA who progressed to SAA were given combined immunosuppressive therapy. The percentage of overall and complete responders was 70.6% and 41.2%, respectively. The level of CD4(+), NK cell ratio decreased but the level of CD8(+) cell increased in MAA children before the treatment. The level of NK and CD4(+) cell was significantly higher in the IS group with the treatment than in the control group. CONCLUSION When childhood MAA is treated with supportive care alone, more than 50% of patients may progress to SAA. Immune mediated pathological mechanism of MAA might be the base of IS therapy. IS therapy is effective and safe for childhood MAA.CIS therapy given to patients with MAA that was progressed to SAA may also be effective.