In Vitro Study of the Function of Dendritic Cells on Stimulating T Lymphocytes Proliferation in Severe Aplastic Anemia

Objective To investigate the function of dendritic cells (DCs) in severe aplastic anemia (SAA).

Methods Fifteen untreated patients, 10 recovered patients with SAA and 12 normal controls were enrolled in this study. Their mDCs were induced from their bone marrow mononuclear cells with rhIL-4, rhGM-CSF and rhTNF in vitro. Then mDCs were co-cultured with allogenic lymphocytes (mixture lymphocyte reaction, MLR). The growth rate of lymphocyte was measured by MTT colorimetry and the concentrations of IL-12 and IFNγ in MLR supernatant were measured by ELISA. The correlation between the growth rate and the concentration of IL-12 or IFNγ was analyzed.

Results When mDCs and lymphocytes were co-cultured at the ratio of 1:50, the growth rate of lymphocytes stimulated with the mDCs from untreated cases was (322.13±171.07)%, which was higher than those stimulated with the mDCs from recovered and controls [(180.90±79.12)%, (192.25±91.93)%] (P<0.05). There was no statistical significance between the growth rates of lymphocytes stimulated with the mDCs from the recovered and controls (P>0.05). The mDCs of 8 recovered cases and 4 controls were co-cultured with allogenic lymphocytes at the ratio of 1:100, 1:50, 1:20 and 1:10, but no statistical significance was found between two groups at each ratio (P>0.05). Cross MLR showed only untreated cases versus normal had statistical significance (P<0.05). The concentrations of IL-12 and IFNγ in MLR supernatant of untreated cases were higher than those of the recovered or controls (P<0.05), but there was no statistical significance between the recovered and controls (P>0.05). The concentration of IL-12 in MLR supernatant correlated positively with the growth rate of lymphocyte (r = 0.529,P=0.001), which was also positively correlated with the concentration of IFNγ (r = 0.381,P=0.024).

Conclusion The function of mDCs to stimulate T lymphocytes proliferation by secretingt IL-12 in SAA was enhanced, which might play an important role in the immunopathogenesis of SAA.