MOLECULAR EVENTS IN ANTIGEN RECOGNITION

辅助诱导子亚群的T细胞识别抗原， 辅助细胞上表达的II类MHC分子。 球状 蛋白质抗原，抗原必须由附件处理 在T细胞识别之前。 小肽可以替代 因为它们可以被T细胞识别， 使用预先固定的辅助细胞或带有Ia的平面膜 呈递抗原 我们最近能够证明 免疫原性肽与Ia分子特异性结合。 通过一组12种这样的肽，我们发现了一种相关性， Ia分子结合特定的 肽和Ia作为限制的能力 相同肽的元素。 此外，我们还提供 证据表明Ia和肽之间形成的复合物是 免疫学相关，并且正是这个部分 被T细胞受体识别。 我们计划扩大我们的 研究抗原-Ia相互作用在T辅助细胞中的作用 细胞反应如下： 1)为了研究多肽的结构特征， 使他们能够与Ia互动。 2)为了鉴定天然存在的 与Ia结合并使这种结合相关的蛋白抗原 活性与这些相同肽的免疫原性有关。 3)鉴定和表征Ia分子内的区域 其形成Ia的抗原结合位点。 4)证明和表征三分子复合物 Ia抗原和T细胞受体之间的联系 5)为了研究Ia-肽相互作用的化学计量， 试图理解为什么一小部分亲和纯化的 Ia似乎能够结合肽。

T cells of the helper-inducer subset recognize antigen and the class II MHC molecules expressed on accessory cells. For globular protein antigens, the antigen must be processed by the accessory cells prior to T cell recognition. Small peptides can substitute for processed antigen since they can be recognized by T cells when prefixed accessory cells or Ia bearing planar membranes are used to present antigen. We have recently been able to demonstrate that immunogenic peptides bind specifically to Ia-molecules. With a panel of 12 such peptides we have found a correlation between the capacity of an Ia molecule to bind a particular peptide and the capacity of that Ia to serve as a restriction element of the same peptide. Furthermore, we have provided evidence that the complex formed between Ia and peptide is immunologically relevant and that it is this moiety that is recognized by the T cell receptor. We plan to extend our investigations of the role of antigen-Ia interactions in T helper cell responses as follows: 1) To investigate the structural characteristics of peptides that enable them to interact with Ia. 2) To identify the peptide regions within a naturally occurring protein antigen that bind to Ia and to correlate this binding activity to the immunogenicity of these same peptides. 3) To identify and characterize the region(s) within Ia molecules that form the antigen binding site(s) of Ia. 4) To demonstrate and characterize the tri-molecular complex between Ia, antigen, and T cell receptor. 5) To investigate the stoichiometry of Ia-peptide interaction in an attempt to understand why a small fraction of affinity purified Ia appears capable of binding peptide.