Kim K H, Shivdasani R A, Thomas D W
J Immunol. 1986 Dec 1;137(11):3393-400.
In this study we examined the mechanism by which a PPD-specific murine T cell hybridoma, 8B2, recognized PPD associated with antigen-presenting cells (APC) in a manner genetically restricted by I-Ad. It was found that PPD-pulsed APC that were glutaraldehyde-fixed and treated with anti-Ia monoclonal antibody (abbreviated as PGM) were unable to stimulate the 8B2 T cells, as expected, due to inhibition caused by antibody binding to the Ia. However, addition of non-antigen-treated, glutaraldehyde-fixed APC (abbreviated as G) to cultures containing 8B2 T cells and PGM restored T cell activation, as determined by IL 2 production. This second non-antigen-specific function provided by the additional APC, G, was attributed to Ia and could be substituted by APC plasma membranes and by soluble membrane extracts. Genetic restriction analysis in which a variety of Ia-positive and Ia-negative cell lines and B cell blasts from different mouse strains were used as PGM or as G showed that each APC provided different Ia determinants that were specifically recognized by the T cells. PGM cells had to express I-Ad in order to present the PPD determinant, whereas the non-antigen-specific function was specific for I-Ad or I-Ab. These results suggest that the anti-Ia antibody does not interfere with the PPD/I-Ad-specific determinant bound by the antigen-specific T cell receptor, but prevents a second non-antigen-specific interaction with another region of the Ia molecule, which is provided by G. These two roles for Ia (antigen-specific and non-antigen-specific) were also found for activation of normal polyclonal PPD-specific T cell responses; thus they are not unique to the 8B2 T cell, but are generally applicable. In addition, T cell interactions with PGM and with G each provide different intracellular activation signals. This was determined by substituting the PGM or the G with either the tumor promoter phorbol 12-myristate 13-acetate (PMA) or the Ca++ ionophore, ionomycin. It was found that 8B2 T cells cultured with PGM and ionomycin, but not with PGM and PMA, were activated for IL 2 production. Neither PMA nor ionomycin in conjunction with G resulted in T cell activation. Taken together, these results indicate that 8B2 T cell activation involves APC Ia antigens in two different ways: one is to contribute to the presentation of the foreign PPD antigen, and a second is a non-antigen-specific Ia-T cell interaction necessary to provide additional intracellular activation signals.(ABSTRACT TRUNCATED AT 400 WORDS)
在本研究中，我们探究了一种PPD特异性的小鼠T细胞杂交瘤8B2，以受I-Ad基因限制的方式识别与抗原呈递细胞（APC）相关的PPD的机制。结果发现，经戊二醛固定并用抗Ia单克隆抗体处理的PPD脉冲APC（简称为PGM），由于抗体与Ia结合导致的抑制作用，无法刺激8B2 T细胞，这正如预期。然而，向含有8B2 T细胞和PGM的培养物中添加未经抗原处理、戊二醛固定的APC（简称为G），可恢复T细胞活化，这通过白细胞介素2的产生来确定。额外的APC（即G）提供的这种第二种非抗原特异性功能归因于Ia，并且可以被APC质膜和可溶性膜提取物替代。使用来自不同小鼠品系的多种Ia阳性和Ia阴性细胞系以及B细胞母细胞作为PGM或G进行的基因限制分析表明，每个APC提供不同的Ia决定簇，这些决定簇被T细胞特异性识别。PGM细胞必须表达I-Ad才能呈递PPD决定簇，而非抗原特异性功能对I-Ad或I-Ab具有特异性。这些结果表明，抗Ia抗体不会干扰抗原特异性T细胞受体结合的PPD/I-Ad特异性决定簇，但会阻止与由G提供的Ia分子另一个区域的第二种非抗原特异性相互作用。Ia的这两种作用（抗原特异性和非抗原特异性）在正常多克隆PPD特异性T细胞反应的激活中也有发现；因此它们并非8B2 T细胞所特有，而是普遍适用。此外，T细胞与PGM以及与G的相互作用各自提供不同的细胞内激活信号。这是通过用肿瘤启动子佛波醇12-肉豆蔻酸酯13-乙酸酯（PMA）或钙离子载体离子霉素替代PGM或G来确定的。结果发现，与PGM和离子霉素一起培养的8B2 T细胞，而非与PGM和PMA一起培养的细胞，被激活产生白细胞介素2。单独的PMA或离子霉素与G一起都不会导致T细胞活化。综上所述，这些结果表明8B2 T细胞活化以两种不同方式涉及APC Ia抗原：一种是有助于呈递外来的PPD抗原，另一种是提供额外细胞内激活信号所必需的非抗原特异性Ia-T细胞相互作用。（摘要截选至400字）
