T cell antigen receptor and chain genes and MHC restriction

1. T细胞受体（TcR）由<alpha>和<beta>链组成。通过转移克隆基因和<beta>链基因，确定了这种<alpha><beta>异源二聚体负责T细胞的双重特异性。为了确定重要的氨基酸残基，我们从I-A^K反应性T细胞克隆MS 202中获得了具有改变的特异性的突变T细胞克隆。一个突变克隆E-3显示出对I-A^D和I-A^d以及I-A^K有反应。这种特异性变化似乎是由于E-o中TcR的结构变化所致，因为E-3中TcR的分子量小于MS 202。然而，TcR和链基因的核苷酸序列<alpha><beta>在MS 202和E-3之间是相同的。发现E-3在糖基化方面存在缺陷。此外，这两个克隆可能表达两种不同链的TcR分子。我们正在确定E-3.2特异性变化的原因。所有的小鼠抑制性T细胞克隆检查显示表达TcR<alpha>和<beta>链基因。我们目前正在利用消减杂交技术克隆抑制性T细胞中特异表达的基因.无论<alpha><beta>T细胞是否被抗原激活，编码TcR和TcR链的mRNA的量几乎不变. NZW<beta>小鼠的TcR链基因可能与（NZB × NZW）F_1小鼠的自身免疫有关。

1. The T cell receptor (TcR) is composed of <alpha> and <beta> chains. By transferring cloned and <beta> chain genes, it was established that this <alpha><beta> heterodimer is responsible for the dual specificity of T cells. However, it is still not known which amino acid residues are important in determining T cell specificities.In order to define important amino acid residues, we derived mutant T cell clones with altered specificities from an I-A^K reactive T cell clone, MS202. One mutant clone, E-3, was shown to respond to I-A^D and I-A^d as well as I-A^K. It seemed that this specificity change was due to the structural change of TcR in E-o as molecular weight of TcR was smaller in E-3 than in MS202. However, nucleotide sequences of TcR <alpha> and <beta> chain genes were identical between MS202 and E-3. It was found that E-3 has a defect in glycosylation. In addition, these two clones might express two kinds of TcR molecules with different chains. We are in a process of determining the cause of specificity change in E-3.2. All murine suppressor T cell clones examined were shown to express TcR <alpha> and <beta> chain genes. We are now in a process of cloning genes specifically expressed in suppressor T cells using the subtraction hybridization.3. The amount of mRNA coding for TcR <alpha> and <beta> chains was found to be almost constant whether T cells are activated by antigens or not.4. The TcR <beta> chain gene of NZW mice seems to contribute to the autoimmunity in (NZB x NZW)F_1 mice.