超抗原SEB在同种异体细胞移植小鼠中诱导的免疫耐受及其特征

Immunotolerance and its characteristics induced by SEB in mice receiving allogenic cell transplantation

目的 探讨超抗原葡萄球菌肠毒素Ｂ（ＳＥＢ）体内诱导的免疫耐受性及其特征。方法 采用ＭＨＣ不同的两种小鼠进行淋巴细胞移植。用流式细胞术和混合淋巴细胞培养技术，检测受体鼠Ｔ 细胞亚群的变化，供体鼠Ｈ－２Ｋｄ分子在受体鼠体内表达的阳性率与免疫应答性。结果（１）注射ＳＥＢ可选择性地降低ＣＤ４＋Ｔ细胞和ＣＤ４＋Ｔ／Ｈ－２Ｋｂ＋细胞的百分率，而不影响ＣＤ８＋Ｔ细胞的数量。在ＳＥＢ注射的２１ ｄ，抑制作用最强，其对ＣＤ４＋Ｔ细胞和ＣＤ４＋Ｔ／Ｈ－２Ｋｂ＋细胞的抑制率分别是６．２４％和２３．３８％。（２）在进行异源性ＭＨＣ淋巴细胞移植时注射ＳＥＢ，于移植细胞后２１ ｄ， 受体小鼠肝脏淋巴细胞上开始表达供体小鼠Ｈ－２Ｋｄ分子，至移植后４０ ｄ，表达率达到高峰７．９０％。与此同时，受体鼠外周淋巴细胞对供体鼠淋巴细胞的免疫应答能力也明显降低。结论ＳＥＢ能诱导小鼠产生免疫耐受，免疫耐受的形成与受体鼠体内ＣＤ４＋Ｔ细胞克隆的明显减少有关。

Aim To explore the immunotolerance and its characteristics induced by staphylococcal enterotoxin B (SEB) in mice receiving allogenenic cell transplantation. Methods By use of flow cytometry and mixed lymphocyte reaction (MLR),the change in T cell subset, expression of MHC molecule and proliferetive response in recipient mice were detected after transplantation. Results(1) SEB decrease selectively the percentages of CD4+T cells and CD4+T/H-2Kb+ cells but had no effect on the number of CD8+cells in C57BL/J mice. The highest inhibitory rates of SEB on CD4+T cells and CD4+T/H-2Kb+ cells were 6.24% and 23.38% respectively, on day 21 after injection of SEB. (2) Expression rete of allo-MHC H-2Kd molecule on hepatic lymphocytes in recipient mice reached to 7.90% on 40 day after receiving allogenenic MHC lymphocyte transplantation and SEB. At the same time, proliferative response of recipient to donor mouse in MLR also decreased significantly. Conclusion SEB-induced immunotolerance is related to distinct reduction in the number of CD4+T cell clones .