T-cell stimulation and cytokine release induced by staphylococcal enterotoxin A (SEA) and the SEAD227A mutant
T-cell stimulation and cytokine release induced by staphylococcal enterotoxin A (SEA) and the SEAD227A mutant
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DOI：
10.1046/j.1365-2567.1997.00141.x
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发表时间：
1997-01-01
期刊：
影响因子：
6.4
通讯作者：
Dannecker, GE
中科院分区：
文献类型：
--
作者：
Holzer, U;Orlikowsky, T;Dannecker, GE
以前的工作表明，由超抗原激活的人细胞毒性T细胞可以裂解主要组织相容性复合物（MHC）II类阳性靶细胞以及涂有单克隆抗体和超抗原缀合物的MHC II类阴性肿瘤细胞。为了降低MHC II类亲和力，并因此降低超抗原葡萄球菌肠毒素A（SEA）与MHC II类分子的不希望的结合，将点突变引入SEA基因。该突变（SEAD 227 A）导致对人白细胞抗原（HLA）-DR的亲和力降低约3-log，但该突变超抗原介导的对抗原标记的肿瘤细胞的细胞毒性与天然超抗原介导的细胞毒性一样有效。因此，我们比较了天然和突变SEA的T细胞活化效力。我们的数据显示，当在原始细胞形成、细胞表面活化标志物的表达和细胞因子释放方面测定静息T细胞的活化时，SEAD 227 A的有效性比天然SEA低4至5个对数。此外，通过MHC II类阴性肿瘤细胞向MHC II类阴性单核细胞呈递SEA或SEAD 227 A不会导致T细胞的显著原始细胞形成、CD 25上调或细胞因子释放。这表明，MHC II类阴性肿瘤细胞的裂解是有效地诱导单克隆抗体靶向超抗原，而静息T细胞的激活需要额外的共刺激信号。
Previous work demonstrated that human cytotoxic T cells activated by superantigens can lyse major histocompatibility complex (MHC) class II-positive target cells as well as MHC class II-negative tumour cells coated with conjugates of monoclonal antibodies and superantigens. In order to decrease MHC class II affinity, and therefore unwanted binding of the superantigen staphylococcal enterotoxin A (SEA) to MHC class II molecules, a point mutation was introduced into the SEA gene. This mutation (SEAD227A) resulted in an approximately 3-log reduction of affinity to human leucocyte antigen (HLA)-DR, but cytotoxicity mediated by this mutant superantigen towards antigen-labelled tumour cells is an efficient as cytotoxicity mediated by the native superantigen. We therefore compared the T-cell activating potency of native and mutated SEA. Our data show that SEAD227A is 4- to 5-log less effective than native SEA when activation of resting T cells is assayed in terms of blast formation, expression of cell surface activation markers and cytokine release. Furthermore, presenting either SEA or SEAD227A to MHC class II-negative mononuclear cells by MHC class II-negative tumour cells did not result in significant blast formation of T cells, up-regulation of CD25 or cytokine release. This suggests that lysis of MHC class II-negative tumour cells is efficiently induced by monoclonal antibody targeted superantigen, while activation of resting T cells requires additional co-stimulatory signals.