Study Of The Relationship Between SDF-1/CXCR4 And Pathogenesis Of Aplastic Anemia

Objective: To study the role of stromal cell-derived factor 1(SDF-1) and CXC chemokine receptor 4( CXCR4) in the pathogenesis of aplastic anemia (AA). Methods: (1) ELISA was used to examine the concentrations of SDF-1αin the supernatant of bone marrow (BM) and plasma of peripheral blood (PB) in the both AA and normal children. (2) Peripheral blood mononuclear cells (PBMNCs) were obtained from the AA and normal children. The ratio between CD~3+ CXCR4~+ PNMNCs and CD3~+ PNMNCs was analyzed by FASC in two groups. (3) Different concentrations of SDF-1 α(0, 10, 50, 100, 250, 500ng/ml) were used to induce the proliferation of active peripheral blood T-cell, which the proliferation rate was evaluated by using incorporated 3~H-TdR. Moreover, anti-CXCR4 antibody was used to assess the inhibiting possibility. (4) The different transmigration capabilities of T-cell between AA and normal PBMNCs were compared by using chemotaxis assay in vitro. The 125ng/ml SDF-1αis used to induce the transmigration of AA and normal children's PBMNCs. Furthermore, in order to assess ability of PBMNCs T-cell transmigration that was induced by SDF-1αin the normal BM supernatant, five normal children's BM supernatants were either directly or combined with monoclonal anti-CXCR4 (10μg/ml) to induce the transmigration of PBMNC of one AA children.. Results: (1) The concentrations of SDF-1α(pg/ml) are 1057±284.33 and 587.5±62.27 in the BM supernatants of the AA and normal children, and are 583.3±219.2 and 606.6±234.32 in PB plasma of both groups. The concentration of SDF-1αin the BM supernatant of AA children is higher than that of normal children, and is also significantly higher than that in the PB plasma of AA children (p<0.05). (2) The percentages of CD3+ and CXCR4+ double positive PBMNCs in CD3+ positive PBMNCs are 10.89% and 3.74% in the AA and normal children, respectively. The CXCR4+ positive cells significantly increased in AA children (p<0.05). (3) The means of incorporated 3H-TdR are 22553.87, 29770.03, 37049.10, 39746.57, 42906.63, 46482.13 in different SDF-1αconcentrations treatment groups. Moreover, anti-CXCR4 antibody can inhibit this action that is induced by SDF-1α. (4) The mean transmigration rates of AA and normal children'sPBMNCs induced by SDF-1αare 18.1% and 9.7%, respectively. The mean transmigration rate of AA's PBMNCs increased significantly (p<0.05). The mean transmigration rates of PBMNCs induced by either normal BM supernatant or anti-CXCR4 treated were 35.4% and 5.36%, respectively. Anti-CXCR4 can obviously block the transmigration effect of normal BM supernatant on PBMNCs (p<0.01). Conclusions: (1) SDF-1αraised up in the bone marrow of AA children. (2) CXCR4+ cells increased in the PB T-cell of AA children. (3) SDF-1 was a co-stimulatory molecule in the activated process of T-lyphocyte, and the stimulus intensity was correlation with the concentration of SDF-1. (4) During the AA occurrence, SDF-1/CXCR4 played an important role in the T-lyphocyte migrating, proliferating, and activating into the bone marrow.