Relationship between immune status after ATG treatment and PNH clone evolution in patients with severe aplastic anemia

OBJECTIVES: To investigate the relationship between immune status and paroxysmal nocturnal hemoglobinuria (PNH) clonal evolution of severe aplastic anemia (SAA) patients who received anti‐human thymocyte globulin (ATG) treatment. METHODS: The clinical data of 102 SAA patients who received ATG were collected and retrospectively analyzed. The remission rate, remission time, response rate, hematopoietic, and immune status were compared. Malignant clones were also observed. RESULTS: The remission rate of the group with PNH clones appeared after treatment was significantly higher than the group without PNH clones. The response rate at 12 months of the groups with PNH clones was significantly higher than the group without PNH clones. The recovery of Hb and Ret % of patients with PNH clones was earlier than the patients without PNH clones. The reduction of percentage of CD8(+)HLA‐DR(+)/CD8(+) and Th1/Th2 ratio of patients with PNH clones was both earlier than the patients without PNH clones. Six patients developed myelodysplastic syndromes (MDS). CONCLUSION: In SAA patients with PNH clones, the cytotoxic T‐cell function and Th1 cell number recovered more quickly and had better response to IST. A small number of SAA patients with or without PNH clones developed MDS malignant clones.