Objective: To explore the role of interleukin-17 (IL-17) in the pathogenesis of severe aplastic anemia (SAA).
Methods: Peripheral blood samples were obtained from 40 SAA patients (25 untreated, 15 recovery) and 10 normal controls from October 2012 to October 2013. The level of IL-17 in peripheral blood was measured with cytometric bead array (CBA). The correlations between IL-17 and T cells subset (CD4(+)/CD8(+)), dendritic cells (DC) subset (mDC/pDC), regulatory T cells (Treg) and hemogram were analyzed.
Results: The serum level of IL-17 in untreated patients was higher than that in recovery patients and normal controls ((17.07 ± 15.18) vs (7.09 ± 3.84) and (3.53 ± 2.08) ng/L, both P < 0.01). Also significant differences existed between the latter two groups (P < 0.05). The ratio of CD4(+)/CD8(+) was (0.32 ± 0.08) in untreated patients and it was lower than that in recovery patients (1.11 ± 0.31, P < 0.01) and normal controls (1.07 ± 0.26, P < 0.01). The ratio of mDC/pDC was (3.16 ± 0.55) in untreated patients was higher than that in recovery patients (1.60 ± 0.43, P < 0.01)and normal controls (1.43 ± 0.38, P < 0.01). The percentage of Tregs in peripheral blood lymphocyte (CD4(+)CD25(+)CD127(dim)/PBL) was 0.80% ± 0.31% in untreated patients and it was lower than that in recovery patients (1.78% ± 0.69%, P < 0.01) and normal controls (2.23% ± 0.66%, P < 0.01). The serum level of IL-17 in untreated SAA patients was related positively with mDC/pDC ratio (r = 0.414, P < 0.05) and negatively with CD4(+)/CD8(+) ratio (r = -0.421, P < 0.05) and CD4(+)CD25(+)CD127(dim)/PBL(r = -0.650, P < 0.01). And significant negative correlations existed between serum IL-17 and white blood cells in untreated patients (r = -0.689, P < 0.01) and recovery patients (r = -0.640, P < 0.05).
Conclusion: The elevated serum level of IL-17 in SAA is related with the immunological status and disease severity.