Objective: To measure the subsets of dendritic cells 1 (DC1) in the bone marrow of severe aplastic anemia (SAA) patients and evaluate the relationships between the CD11c+CD83+ cells and Th1 cells, CD3+CD8+ cells or hematopoietic function and explore the role of DC1 in the pathogenesis of SAA.
Methods: By FACS, the quantities and ratios of CD11c+CD1a+ cells, CD11c+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 reticulocyte absolute value (Ret) or neutrophil absolute value (ANC), between Th1 cells and CD3+CD8+ cells, Ret or ANC, between CD11c+CD83+ cells, and Th1 cells, CD3+CD8+ cells, Ret or ANC were evaluated.
Results: In normal controls' bone marrow, the percentages of Th1 cells, CD11c+CD1a+ cells, CD11c+CD83+ cells and the ratio of CD11c+CD83+/CD11c+CD1a+ were (0.42 +/- 0.30)%, (0.38 +/- 0.29)%, (0.37 +/- 0.32)% and 1.07 +/- 0.10, respectively. In untreated SAA patients, they were (4.87 +/- 0.54)%, (1.73 +/- 0.24)%, (3.38 +/- 0.56)% and 2.21 +/- 0.32 respectively, which were higher than that in normal controls (P < 0.01). In recovering SAA patients, the percentages of Th1 cells, CD11c+CD1a+ cells and CD11c+CD83+ cells decreased significantly to (0.53 +/- 0.22)%, (0.61 +/- 0.23)%, (0.65 +/- 0.22)%, respectively (P < 0.01). The ratio of CD11c+CD83+/CD11c+ CD1a+ in recovering SAA patients decreased to 1.37 +/- 0.25, which was similar to that in normal controls (P > 0.05). The percentage of CD3+CD8+ cells in untreated SAA patients was (32.32 +/- 10.22)%, and in recovering SAA patients decreased to (13.67 +/- 5.24)% (P < 0.01). The percentage of CD3+CD8+ cells in SAA patients was negatively correlated with their Ret and ANC (P < 0.05), while their Th1 cell percentages were positively correlated with their CD3+CD8+ cells (P < 0.01), and negatively correlated with their Ret and ANC (P < 0.01). SAA patient's CD11c+CD83+ cell percentages were positively correlated with their Th1 cell and CD3+CD8 cells (P < 0.01, P < 0.05), but negatively with their Ret and ANC (P < 0.01).
Conclusion: Both immature DC1 and activated DC1 increased in the bone marrow of SAA patients, and the balance of DC1 subsets shifted from stable form to active one, which might promote Th0 cells to polarize to Th1 cells, and cause the over-function of T lymphocytes and hematopoiesis failure in SAA.