Objective:To investigate the role of the IgG subtypes (IgG1 and IgG2a) in anti-glycoprotein (GP) Ⅰbα antibody-induced platelet clearance.Methods:Venous blood was collected from healthy volunteers, and platelets were separated. The phagocytosis of human platelets by human acute monocytic leukemia cells (THP-1 cells) induced by different anti-GPⅠbα antibodies (AN51, AK2, HIP1, TM60, VM16d, WM23, and SZ2) was detected by flow cytometry. The effects of the AN51 full-length antibody, F (ab') 2, and Fab fragments on platelet phagocytosis by THP-1 cells were detected by flow cytometry. Then, the Fc blocking antibody 2.4G2 and normal rat IgG2a or IgG1 were injected into C57BL/6J mice via the posterior ocular vein, and their effects on platelet reduction induced by R300 were detected by a hematology analyzer. Results:Compared with IgG1, the IgG2a subtype of anti-GPⅠbα antibodies induced the phagocytosis of platelets by THP-1 cells in vitro ( P<0.05). In contrast to the AN51 full-length antibody, neither AN51 F (ab') 2 nor the Fab fragment could induce THP-1 cells to phagocytose platelets ( P<0.05). Compared with the control group, anti-mouse GPⅠbα R300-induced thrombocytopenia in mice was reduced at 2, 4, and 6 h after the injection of Fc blocking antibody 2.4G2 ( P<0.05). Similarly, R300-induced thrombocytopenia in mice was reduced at 2, 4, and 6 h after the injection of rat IgG2a ( P<0.05) . Conclusion:IgG2a plays an important role in anti-GPⅠbα-induced clearance.

Objective:To investigate the role of the IgG subtypes (IgG1 and IgG2a) in anti-glycoprotein (GP) Ⅰbα antibody-induced platelet clearance.Methods:Venous blood was collected from healthy volunteers, and platelets were separated. The phagocytosis of human platelets by human acute monocytic leukemia cells (THP-1 cells) induced by different anti-GPⅠbα antibodies (AN51, AK2, HIP1, TM60, VM16d, WM23, and SZ2) was detected by flow cytometry. The effects of the AN51 full-length antibody, F (ab') 2, and Fab fragments on platelet phagocytosis by THP-1 cells were detected by flow cytometry. Then, the Fc blocking antibody 2.4G2 and normal rat IgG2a or IgG1 were injected into C57BL/6J mice via the posterior ocular vein, and their effects on platelet reduction induced by R300 were detected by a hematology analyzer. Results:Compared with IgG1, the IgG2a subtype of anti-GPⅠbα antibodies induced the phagocytosis of platelets by THP-1 cells in vitro ( P<0.05). In contrast to the AN51 full-length antibody, neither AN51 F (ab') 2 nor the Fab fragment could induce THP-1 cells to phagocytose platelets ( P<0.05). Compared with the control group, anti-mouse GPⅠbα R300-induced thrombocytopenia in mice was reduced at 2, 4, and 6 h after the injection of Fc blocking antibody 2.4G2 ( P<0.05). Similarly, R300-induced thrombocytopenia in mice was reduced at 2, 4, and 6 h after the injection of rat IgG2a ( P<0.05) . Conclusion:IgG2a plays an important role in anti-GPⅠbα-induced clearance.

Objective To investigate the influencing factors involved in the establishment of a C57BL/6 J model of metastatic melanoma in the lung,including the way of tumor inoculation,the number of inoculated cells and the time of tumor formation. Methods Mouse melanoma B16F10 cells were cultured in vitro. 1)Eighteen healthy male C57BL/6 J mice were randomly divided into three groups. Mice in each group received 100 μL cell suspension(including 3 ×106 melanoma cells)via intravenous,intraperitoneal and subcutaneous injection,respectively. After two weeks,the mice were killed and dissected,and the tumor growth and metastasis were observed. 2)Eighteen male mice were randomly divided into three groups. Mice in each group were injected with 3 ×106cells,1 ×106cells, and 3 ×105cells through the tail vein,respectively. After two weeks,mice were killed and dissected,and the tumor growth and metastasis were observed. 3)Eighteen male mice were randomly divided into three groups. Mice in each group were injected with 1×106cells though the tail vein. Mice were killed and dissected after one week, two weeks and three weeks, respectively. The growth and metastasis of tumor were observed. Results 1)The success rate of lung metastasis was 100% in the mice with intravenous injection,but not in mice receiving intraperitoneal injection and subcutaneous injection. 2)The size of metastatic melanoma nodules were moderate in mice inoculated by 1 ×106cells. The number of melanoma metastatic foci was too high in the mice inoculated with 3 ×106cells,but too low in the mice inoculated with 3 ×105cells. 3)Significant metastatic melanoma foci were observed in the mice killed and dissected after two weeks with no death. The number of melanoma foci in the lung was too high in the mice killed after three weeks,while was too low in the mice killed at one week after tumor cell inoculation. Conclusions Intravenous injection of 1×106mouse melanoma cells into C57BL/6 J mice and killed after two weeks is an optimal method for establishment of a mouse model of metastatic melanoma in the lung, and is worth of recommendation.

Objective:To investigate the effect of Artesunate (Art) on the expression of transferrin receptor (TtR)in K562/ADM cells.Methods:The drug-resistant K562/ADM cells were cultured with 1000 ng/mL doxorubicin for two weeks followed by Artesunate treatment with different concentrations (12.5 μg/mL,25μg/mL and 50 μg/mL) or different time (12 h,24 h,36 h,and 48 h).The content of transferrin receptor in K562/ADM cells was determined by flow cytometry.The effect of Artesunate on the expression of transferrin receptor protein in K562/ADM cells was measured by Westem blot.Cell counting kit-8 (CCK-8) assay was used to evaluate inhibitory effect of Art combined with doxorubicin (ADM) in K562/ADM cells.The reversal index was defined as the IC50 of the experimental group divided by the IC50 of the control group in K562/ADM cells.Results:Art effectively decreased the content of transferrin receptor and the expression of transferrin receptor protein in K562/ADM cells in a dose-dependent manner.Moreover,Art also inhibited transferrin receptor protein expression in K562/ADM cells in a time-dependent manner.The different concentrations of Art(12.5 μg/mL,25μg/mL and 50 μg/mL) could induce reversal of drug-resistance with the reversal index being 1.38,2.12 and 2.95 times (P＜0.05).Art inhibited cell proliferation of K562/ADM cells,and the IC50 werel9.7 μmol/L.Conclusions:Art effectively down-regulated the transferrin receptor content as well as transferrin receptor protein expression in K562/ADM cells,which resulted in reversal of drug resistance of K562/ADM cells.Art also inhibited K562/ADM cells proliferation,which has great value in clinical treatment of leukemia.

Objective: To establish primary immune thrombocytopenia (ITP) animal model induced by anti-platelet membrane glycoprotein GPⅠbα antibodies AN51 and R300. Methods: Twenty guinea pigs (6-8 week) were divided into 4 groups. Five guinea pigs in each group were intravenously injected with different doses of AN51 (0.05, 0.1, 0.2 μg/g) and 0.2 μg/g IgG as control. The whole blood was collected from inner angular venous plexus. Platelets number was determined by an automated cell counter and Swiss-Jim method. Then, the similar protocol was used to establish ITP nude mice model by intraperitoneal injection of different concentrations of anti-platelet GPⅠbα antibody R300, respectively. Results: ①Five minutes after intravenous injection of AN51 at 0.05, 0.1 and 0.2 μg/g, the platelet counts of guinea pigs reduced about 0-5%, 50%-60% and 70%-80% compared to the control group, respectively. The difference was statistically significant (P<0.01) . ②Six hours after intraperitoneal injection of R300 at 0.05, 0.1, 0.2 μg/g, the platelet counts of nude mice decreased about 20%-30%, 60%-70% and 80%-90% compared to the control group, respectively. The difference was statistically significant (P<0.01) . The nude mice, injected 0.2 μg/g R300 once a day for 2 weeks, showed typical ITP clinical manifestations including large number of petechiaes or ecchymoses on limbs, head and abdomen. Conclusion AN51 at 0.2 μg/g and R300 at 0.2 μg/g could establish stable ITP model in guinea pigs and nude mice respectively.