Changes of Subsets of DC 1 in the Bone Marrow of Severe Aplastic Anemia Patients.

Objective To measure the changes of subsets of dendritic cells 1 (DC1) in the bone marrow of severe aplastic anemia (SAA) patients and evaluate the relationships between the CD_11c⁺CD₈₃⁺cells and Th1 cells, CD₃⁺CD₈⁺ cells or hematopoietic function.

Methods By FACS, the quantity and ratio of CD_11c⁺CD_1a⁺ cells, CD_11c⁺CD₈₃⁺ cells, Th1 cells, and CD₃⁺CD₈⁺ cells in the bone marrow of SAA patients and normal controls were detected respectively. The relationships between CD₃⁺CD₈⁺ cells and Ret or ANC, between Th1 cells and CD₃⁺CD₈⁺ cells, Ret or ANC, between CD_11c⁺CD₈₃⁺ cells, and Th1 cells, CD₃⁺CD₈⁺ cells, Ret or ANC were evaluated.

Results In normal control’s bone marrow, the percentages of Th1 cells, CD_11c⁺CD_1a⁺ cells, CD_11c⁺CD₈₃⁺ cells and ratio of CD_11c⁺CD₈₃⁺ /CD_11c⁺CD_1a⁺ was 0.42±0.30%, 0.38±0.29%, 0.37±0.32% and 1.07±0.10 respectively. In the untreated SAA patient’s bone marrow, they were 4.87±0.54%, 1.73±0.24%, 3.38±0.56% and 2.21±0.32 respectively, and increased markedly(p<0.01). In recovering SAA patient’s bone marrow, the percentages of Th1 cells, CD_11c⁺CD_1a⁺ cells and CD_11c⁺CD₈₃⁺ cells decreased significantly[0.53±0.22%, 0.61±0.23%, 0.65±0.22%, respectively (p<0.01)]. The ratio of CD_11c⁺CD₈₃⁺/CD_11c⁺ CD_1a⁺ of recovering SAA patients was 1.37±0.25 which was similar to that of normal controls (p>0.05). The percentages of CD₃⁺CD₈⁺ cells of untreated SAA patients was 32.32±10.22%, and that of recovering SAA patients decreased to 13.67%±5.24 significantly (p<0.01). The percentages of CD₃⁺CD₈⁺ cells of SAA patients were correlated to their Ret and ANC (P<0.05) negatively. Their Th1 cell percentages were correlated to their CD₃⁺CD₈⁺ cells positively (P<0.01), but to their Ret and ANC negatively(p<0.01). SAA patient’s CD_11c⁺CD₈₃⁺ cell percentages were correlated to their Th1 cell and CD₃⁺CD₈⁺ cells positively (P<0.01, P<0.05), but to their Ret and ANC negatively(p<0.01).

Conclusion Both immature DC1 and activated DC1 increased in the bone marrow of SAA patients, and the balance of subsets of DC1 shifted from stable form to active one, which might promote Th0 cells to polarize to Th1 cells, then cause the over-function of T lymphocytes and hematopoietic failure in SAA.