Quantity and Functional Changes of Subsets of Th Cells in the Bone Marrow of Severe Aplastic Anemia Patients.

Objective To evaluate the quantity and functional changes of subsets of Th cells in the bone marrow of severe aplastic anemia (SAA) patients and the relationship between these changes and the patient hematopoietic function.

Methods By FACS, the quantity and ratio of Th1 cells and Th2 cells, the percentage of CD₃⁺CD₈⁺ cells in the bone marrow were detected in 24 patients with SAA at active phase, 15 patients with SAA at recovery phase, and 16 normal controls respectively. By radioimmunoassay, the levels of cytokines of Th1 type (TNF-α), or Th2 type (IL-4) in the serum of 20 patients with SAA at active phase, 12 patients with SAA at recovery phase, 16 normal controls were measured respectively. The relationships between CD₃⁺CD₈⁺ cells, TNF-α and Ret, ANC were evaluated; the relationships between Th1 cells and CD₃⁺CD₈⁺ cells, TNF-α or Ret, ANC were evaluated; the relationships between IL-4, balance of Th1/Th2 and Ret, ANC were also evaluated.

Results The percent of Th1 cells, Th2 cells, and ratio of Th1/Th2 in bone marrow of patients with SAA at active phase was: 4.87±2.64%, 0.41±0.26%, 21.22±5.07, were higher than those of normal controls: 0.42±0.30% (p<0.01), 0.24±0.17% (p<0.05), 1.57±0.93(p<0.01) respectively, and all of these decreased to normal levels at recovery phase (p>0.05); the percent of CD₃⁺CD₈⁺ cells decreased from 32.32±18.69% at active phase to 13.76±2.96% at recovery phase significantly (p<0.01); the serum levels of TNF-α, IL-4 at active phase was 4.29±3.15ng/ml and 1.24±0.73 ng/ml respectively, higher than those of normal controls(1.21±1.16 ng/ml, 1.18±0.97 ng/ml), but only the difference of TNF-α was significant (p<0.01); in recovery SAA patients, the serum levels of TNF-α significantly decreased to 1.46±1.41 ng/ml (p<0.01), and the levels of IL-4 increased continually markedly to 3.05±1.94 ng/ml; the CD₃⁺CD₈⁺ cells and TNF-α of patients correlated with Ret (p<0.05;p<0.05) and ANC (p<0.05;p<0.05) negatively, Th1 cells correlated with CD₃⁺CD₈⁺ cells and TNF-α positively (p<0.01;p<0.05), the Ret and ANC negatively(p<0.01;p<0.01), IL-4 and the balance of Th1/Th2 correlated with Ret and ANC positively (p<0.05;p<0.01) (p<0.01;p<0.01).

Conclusion The formation of bone marrow failure in SAA might be caused not only by the increase of Th1 cells, Th1 type effective cells and cytokines, but also by unsufficient compensation of Th2 cells and Th2 type cytokines, which shifted the balance of Th1/Th2 to Th1.