- Diagnosed with moderate or more severe AA according to the diagnostic criteria of AA. The severity classification is: Stage I - Mild - Other than the stages below; Stage II - Moderate - At least two of the following conditions are met: Reticulocyte <60,000/microliter, Neutrophil <1,000/microliter, Platelet <50,000/microliter; Stage III - Moderately severe - At least two of the following conditions are met and regular red blood cell transfusion (a need for transfusion of >=2 units per month) is required: Reticulocyte <60,000/microliter, Neutrophil <1,000/microliter, Platelet <50,000/microliter; Stage IV - Severe - At least two of the following conditions are met: Reticulocyte <20,000/microliter, Neutrophil <500/microliter, Platelet <20,000/microliter; Stage V - Very severe - At least one of the following conditions is met in addition to neutrophil <200/microliter: Reticulocyte <20,000/microliter, Platelet <20,000/microliter.