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。 Objective To investigate the in vivo immune tolerance induced by superantigen staphylococcal enterotoxin B (SEB) and its characteristics. Methods Two different MHC mice were used for lymphocyte transplantation. Flow cytometry and mixed lymphocyte culture techniques were used to detect the changes of T lymphocyte subsets in recipient mice and the positive rate and immune response of H-2Kd in donor rat. Results (1) SEB injection could selectively decrease the percentage of CD4 + T cells and CD4 + T / H-2Kb + cells without affecting the number of CD8 + T cells. On the 21st day after SEB injection, the inhibitory effect was the strongest, and the inhibitory rates on CD4 + T cells and CD4 + T / H-2Kb + cells were 6.24% and 23.38%, respectively. (2) SEB was injected in allogeneic MHC lymphocyte transplantation, and donor H-2Kd molecules began to express on the donor’s liver lymphocytes 21 days after transplanted cells. At 40 days after transplantation, the expression rate Reached a peak of 7.90%. At the same time, the ability of recipient mice peripheral lymphocytes to donor rat lymphocytes immune response was significantly reduced. Conclusion SEB can induce immune tolerance in mice, and the formation of immune tolerance is related to the significant reduction of CD4 + T cell clones in recipient mice.