| [Objective]The aim of this study is to investigate the the roles of chimerism level after haploidentical bone marrow cell transplantation on GVT and GVHD,and the mechanism of GVT and GVHD;to investigate whether whole tumor cell vaccination strategies can be effectively used in combination with BMT to stimulate GVT.According to the analysis of our experiment and previous studies,we discuss the mechanism of GVT and GVHD.[Methods]①25 BALB/c mice were randomly divided into 3 group: control group(group C,5),mixed chimerism group(group A,10),full donor chimerism group(group B,10).5 BALB/c mice of group C were only inoculated with Renca ce11(2.6×10~6).10 mice of group A were conditioned with 4Gy irradiation,followed by infusion by bone marrow cell of CB6F1 mice on day 1,then inoculated with Renca cell(2.6×10~6)on day 8.10 mice of group B were conditioned with 8Gy irradiation,followed by infusion by bone marrow cell(5×10~6)of CB6F1 mice on day 1,then inoculated with Renca cell(2.6×10~6)on day 8.Tumor growth was monitored every 4 day.In group A and B,all mice were analyzed by FACScan cytometer on days 14,21,and 28 after BMT.mice were killed when 32 day after inoculation with tumor cell and collected blood of all mice.all tumors were taken out to be weighed,then were cut into 2 parts.The first part of tumors were then fixed in 10%buffered formalin,embedded in paraffin, and cut into 5 um slices.The sections were stained with H&E.The second part was shattered to determine the expression of Fas by western blot.IL-2,IFN-γof Hematoplasma was detected by sandwich-ELISA kits.②26 BALB/c mice were randomly divided into 3 group:control group(group F,6),BMT group (group D,10),BMT+immunization group(group E,10).5 BALB/c mice of group F were only inoculated with Renca cell(2.6×10~6).10 mice of group D were conditioned with 8Gy irridation,followed by infusion by bone marrow cell of CB6F1 mice on day 1,then inoculated with Renca cell(2.6×10~6)on day 8.10 mice of group E were conditioned with 8Gy irridation,followed by infusion by bone marrow cell(5×10~6)of CB6F1 mice on day 1,immunized s.c.on the back with 5×10~5 irradiated Renca tumor cells on day 9,16.All mice of 3 group were inoculated with Renca cell(2.6×10~6)on day 8.In group D and E,all mice were analyzed by FACScan cytometer on days 14,and 28 day after BMT.mice were killed when 32 day after inoculation with tumor cell and collected blood sample. All tumors were taken out to be weighed,then were cut into 2 parts.The first part of tumors were then fixed in 10%buffered formalin,embedded in paraffin,and cut into 5 um slices.The sections were stained with H&E and examined by TUNEL.The second part was shattered to determine the expression of Fas by western blot.IL-2,IFN-γ,of Hematoplasma was detected by sandwich-ELISA kits.[Results]1 The results of chimera showed that engraftments of group A remained mixed donor chimerism and unstable,tended to decrease after 14 days. And that of group B,D and E were full donor chimerism,and the chimerism of those remained above 90%and preserved even after 28 days.2 The size and tumor growth rate in the groups B were lower than that in group A and C(p＜0.01).The tumor suppressing rates of the groups B was 52%.The area of tumor necrosis and the level of IL-2,IFN-γ,in the groups B were higher than groups A and C(p＜0.01).But there was no expression of Fas protein on the tumor of each group.3 The tumor in the groups E was lower in the size than group D and F(p＜0.01,p＜0.05).The tumor suppressing rates of the group D and E is 54%,60% respectively.The area of tumor necrosis of the group E was higher than groups F and D(p＜0.01),and the difference of that was also statistically significant between group D and E(p＜0.05).The level of IL-2 and IFN-γof groups E were higher than group D and F(p＜0.05,p＜0.01).Compaired with group D and F, expression of Fas protein of group E increased significantly,and the apoptosis index was significantly higher(p＜0.01).[Conclusions]Stable full donor chimerism status after haploidentical allogeneic bone marrow cell transplant is the basis of GVT;haploidentical bone marrow cell transplantation may stimulate the mice systemic GVT immunity;the mechanism of GVT after haploidentical allogeneic bone marrow cell transplantation may be tumor necrosis increased,and has nothing to do with apoptosis;haploidentical bone marrow cell reconstitution provide a platform for antigen immunization;Haploidentical allogeneic bone marrow cell transplantation in combination with antigen immunization may stimulate the mice stronger systemic GVT immunity,but not GVHD;the mechanism of GVT after haploidentical allogeneic bone marrow transplantation associated with antigen immunization may be the promotion of tumor necrosis and apoptosis,with the increase in apoptosis of the Fas protein expression increases.GVT is separated from GVHD after haploidentical bone marrow cell transplantation.
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