| BackgroundA variety of blood system diseases,such as acute lymphoblastic leukemia,acute and chronic myeloid leukemia and severe aplastic anemia,are still major life-threatening diseases.Allogeneic bone marrow transplantation is to pretreat the recipient with radiotherapy or chemotherapy in order to remove the hidden tumor cells and abnormal cloned cells in the body,and then transplant the donor hematopoietic stem cells to the recipient.So that its hematopoietic and immune function can be reconstructed to achieve the purpose of treatment.At present,allogeneic bone marrow transplantation is also an effective and recognized method for the treatment of hematological diseases,immunodeficiency diseases and solid tumors.However,complications such as infection,tumor recurrence and graft-versus-host disease after allogeneic bone marrow transplantation are still urgent problems to be solved.After pretreatment with allogeneic bone marrow radiotherapy,the body is in the immune deficiency stage for a long time,which leads to the decrease of the number and function of T cell output.After transplantation,T lymphocytes,B lymphocytes and natural killer cells were particularly slow in the process of reconstruction.As immune effector and regulatory cells,T cells can provide immune protection for receptors after allogeneic bone marrow transplantation,and also play a key role in graft anti-tumor effect.Therefore,the rapid recovery of early immune reconstruction of T lymphocytes after transplantation is the key to prevent post-transplantation infection and graft-versus-host disease.Promoting the effective reconstruction of T lymphocytes after transplantation has been a hot issue in the field of allogeneic bone marrow transplantation.At present,donor lymphocyte infusion is a common method to accelerate T lymphocyte reconstruction after transplantation.however,this operation is relatively complex and easy to cause difficult to control,serious graft-versus-host disease.The methods in the research stage include providing a new microenvironment for T cell differentiation and development,such as thymus transplantation,which is relatively difficult to obtain donors.This study envisages whether a substance that accelerates the proliferation of T lymphocytes can accelerate the reconstruction of T cells after transplantation.Staphylococcal enterotoxin C is a typical superantigen produced by Staphylococcus aureus.It can directly bind to major histocompatibility complex class II molecules,stimulate the proliferation of a large number of T cells without antigen presenting cell treatment,and activate NK cells,B cells and secrete a variety of cytokines.It is an effective T lymphocyte activator.Its application in allogeneic bone marrow transplantation,using its superantigen characteristics of non-specific stimulation of T cell expansion,will have a good application prospect in improving the efficiency of immune reconstruction after transplantation.ObjectiveTo explore the effects of intraperitoneal administration of staphylococcal enterotoxin C on T cells reconstitution after allogeneic bone marrow transplantation.The purpose of this study was to explore a new method which can not only effectively promote the early reconstruction of T cells after allogeneic bone marrow transplantation,but also be easy to operate.Methods1.Intra bone marrow-bone marrow transplantationBALB/C male mice were used as recipients and C57BL/6 male mice as donors.the recipient mice were pretreated with systemic irradiation 12 hours before transplantation.the total dose of irradiation was 6.5Gy[18]and the dose rate was 1Gy/min.The femur and tibia of C57BL/6 donor rats(removing muscle as much as possible)were taken from the experimental platform of SPF room,and the bone marrow was taken under aseptic condition to make single cell suspension,and the cell density was adjusted to 1×109/mL.The donor bone marrow cell suspension was quickly injected into the tibial medullary cavity of the recipient mice after puncture through the knee joint surface with a microsyringe.2.Grouping and administration methodsThey were randomly divided into two groups with 10 rats in each group.The experimental group was given staphylococcal enterotoxin C(100μL/g)and the control group was given the same dose of normal saline.The weight change,hair,diarrhea and so on of the recipient mice were detected every day.3.Reconstruction after allogeneic bone marrow transplantation and its effect analysisTwo weeks after transplantation,the peripheral blood and spleen of the recipient rats were taken and the corresponding fluorescent labeled antibodies(PE-H-2Kb,APC-CD8a,PE/Cy7-CD4,PerCP/Cy5.5-CD45)were added.The implantation status was examined by flow cytometry.the proportion of T lymphocyte subsets and the proportion of CD44 and CD621 in the initial T lymphocytes were analyzed.The secretion of cytokines IFN-γ,IL-2 and TNF-α in mice plasma was detected by ELISA.Graft-versus-host disease was observed and recorded:the survival of recipient mice was observed every other day after transplantation,and the changes of body weight,posture,hair removal and diarrhea degree were recorded,and the clinical score of graft-versus-host disease was carried out.ResultsPercentage of CD8+T cells in experimental group and control group was(12.63±1.33)%and(6.67±0.53)%respectively,there was significant difference between pairwise comparisons(P<0.05),and percentage of CD4+T cells of the spleen and the peripheral blood in experiment group(1.798±0.110)%and(1.470±0.075)%was significantly higher than control group(1.418±0.069)%and(1.112±0.064)%(P<0.05).The levels of IFN-y,IL-2 and TNF-α in experiment group(383.7±49.22)pg/mL,(17.49±1.434)pg/mL and(144.9±14.38)pg/mL was significantly higher than control group(230.0±13.17)pg/mL,(12.38±0.759)pg/mL and(102.0±7.58)pg/mL(P<0.05).There was no obvious graft-versus-host disease in both groups.ConclusionAllogeneic bone marrow transplantation was successfully implanted.Intraperitoneal administration of staphylococcal enterotoxin C could effectively promote the early reconstitution of T lymphocytes without obvious graft versus host disease in the recipient mice after allogeneic bone marrow transplantation. |
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