Study on the Pathways to Damage Hematopoiesis by CD8+ Effector T Cells of the Patients with Severe Aplastic Anemia

To investigate the quantity and their pathways to damage hematopoietic cells of CD8+CD25+ and CD8+HLA-DR+ effector T cells in peripheral blood (PB) of the patients with severe aplastic anemia(SAA) and explore the heterogeneous immunopathogenesis of SAA further.

The quantity of CD8⁺CD25⁺and CD8⁺HLA-DR⁺ cells in PB and the expressions of perforin, granzyme B, tumor necrosis factor-β(TNF -β) and FasL of 29 SAA (14 untreated and 15 recovered) patients and 12 normal controls were analyzed by flow cytometry.

The ratio of CD8⁺CD25⁺T cells in CD8⁺ T cells was (3.67±2.58)% in untreated SAA patients, (5.19±4.29)% in recovered patients and (4.84±2.31)% in normal controls, and the ratios of CD8⁺CD25⁺T cells in CD3⁺ cells in three groups were (2.25±1.35)%, (2.98±1.35)% and (2.11±1.88)% respectively. There was no statistic difference among 3 groups(P>0.05). The ratio of CD8⁺HLA-DR⁺T cells in CD8⁺T cells was (39.30±8.13)% in untreated patients, which was significantly higher than that of recovered patients[(20.65±5.38%)] and controls [(18.34±6.68%)](P<0.001). There was no statistic difference between recovered patients and controls(P>0.05). CD8⁺HLA-DR⁺T cells in CD3⁺ cells was (27.81±7.10)% in untreated group, higher than that of recovered patients (12.02±3.03)% and controls(8.50±2.33)%(P<0.01). And the ratio in recovered group was higher than in control group(P<0.05). The expressions of perforin, granzyme B, TNF-β and FasL of CD8⁺HLA-DR+ T cells of untreated SAA patients were 8.51% A96.08% A72.11% and 94.25% respectively, higher than those of recovered patients(1.78% A85.20% A34.38% A51.20%)and controls(1.86% A82.09% A17.92% A32.91%). There was no statistic difference between recovered patients and controls(P>0.05).

There were elevated quantity of CD8⁺HLA-DR⁺ T cells and high expressions of perforin, granzyme B, TNF-β and FasL in SAA, which might contribute to the bone marrow failure of SAA.

No relevant conflicts of interest to declare.