Expression and T cell recognition of hybrid antigens with amino-terminal domains encoded by Qa-2 region of major histocompatibility complex and carboxyl termini of transplantation antigens.
Expression and T cell recognition of hybrid antigens with amino-terminal domains encoded by Qa-2 region of major histocompatibility complex and carboxyl termini of transplantation antigens.
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DOI：
10.1084/jem.161.5.935
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发表时间：
1985-05-01
期刊：
影响因子：
--
通讯作者：
Hood L
中科院分区：
文献类型：
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作者：
Stroynowski I;Forman J;Goodenow RS;Schiffer SG;McMillan M;Sharrow SO;Sachs DH;Hood L
通过构建杂交I类基因和DNA介导的基因转移相结合的方法，分析了BALB/c Crgl小鼠Qa-2a区Q6基因的编码潜力。通过Q6基因的5'编码区和编码移植抗原（Kd、Dd或Ld）的基因的3'编码区或相反的外显子改组产生重组基因。这些杂交I类基因中的一些在转染的小鼠成纤维细胞（L细胞）中表达。由Q6基因的5'末端和Ld基因的3'末端编码的杂交I类分子沉淀为与β 2-微球蛋白缔合的45，000 molwt分子。杂交蛋白的表达表明，结构Q6基因上游的5'侧翼区的926个碱基对含有在L细胞中作为转录起始位点起作用的启动子。Q6基因的3'部分似乎是小鼠成纤维细胞中缺乏完整Q6和杂合Ld/Q6基因的细胞表面表达的原因。因此，Q6 I类基因的这一部分可能在组织特异性表达中起调节作用。杂交Q6蛋白的血清学分析表明，Q6可能是CR（H-2交叉反应）抗原的结构基因，通常发现在淋巴细胞亚群。如果该鉴定是正确的，Q6基因将定义一类新的I类基因，其编码约40，000 mol wt分子并携带特征性截短的胞质尾。用Q6杂合基因转染的L细胞的分析也证明，对Qa-2a区编码的抗原特异的细胞毒性T细胞识别Q6融合产物的氨基末端α 1-α 2结构域。这种识别可以被抗Qa-2a同种抗血清和与Q6杂交体的α 3-β 2-微球蛋白部分反应的单克隆抗体阻断。我们提出，靶分子上的抗Qa-2a细胞毒性T淋巴细胞特异性表位的结构要求与移植抗原上的抗H-2同种异体反应性细胞毒性T淋巴细胞决定簇相同，并且靶识别的机制在两种情况下是相似的。这种解释与在两类I类分子中发现的以下结构相似性一致：（a）Kd和Q6 α 1-α 2结构域共享血清学上定义的表位。（400字处截断摘要）
Coding potential of the Q6 gene from the Qa-2a region of BALB/c Crgl mice was analyzed by a combination of hybrid class I gene construction and DNA-mediated gene transfer. Recombinant genes were created by exon shuffling of the 5' coding region of the Q6 gene and the 3' coding region of a gene encoding a transplantation antigen (Kd, Dd, or Ld), or the inverse. Some of these hybrid class I genes were expressed in the transfected mouse fibroblasts (L cells). The hybrid class I molecules encoded by the 5' end of the Q6 gene and the 3' end of the Ld gene precipitated as 45,000 mol wt molecules associated with beta 2- microglobulin. The expression of the hybrid proteins indicates that 926 basepairs of the 5' flanking region upstream of the structural Q6 gene contain a promoter that functions as a transcription initiation site in L cells. The 3' portion of the Q6 gene appears to be responsible for the lack of cell surface expression of the intact Q6 and the hybrid Ld/Q6 genes in mouse fibroblasts. Accordingly, this portion of the Q6 class I gene may play a regulatory role in tissue-specific expression. Serological analyses of hybrid Q6 proteins suggested that Q6 may be a structural gene for CR (H-2 crossreactive) antigen found normally on subpopulations of lymphocytes. If this identification is correct, Q6 gene will define a new category of class I genes encoding approximately 40,000 mol wt molecules and carrying a characteristic truncated cytoplasmic tail. Analysis of L cells transfected with Q6 hybrid genes demonstrated also that the cytotoxic T cells specific for Qa-2a region- coded antigens recognize the amino-terminal alpha 1-alpha 2 domain of Q6 fusion products. This recognition can be blocked by anti-Qa-2a alloantiserum and monoclonal antibodies reactive with the alpha 3-beta 2-microglobulin portion of the Q6 hybrids. We propose that the structural requirements for the anti-Qa-2a cytotoxic T lymphocyte- specific epitopes on target molecules are the same as for anti-H-2- alloreactive cytotoxic T lymphocyte determinants on transplantation antigens and that the mechanism of target recognition is similar in both cases. This interpretation is consistent with the following structural similarities found in both categories of class I molecules: (a) Kd and Q6 alpha 1-alpha 2 domains share serologically defined epitopes.(ABSTRACT TRUNCATED AT 400 WORDS)