Olson R R, Reuter J J, McNicholl J, Alber C, Klohe E, Callahan K, Siliciano R F, Karr R W
Department of Veterans Affairs Medical Center, University of Iowa College of Medicine, Iowa City.
Hum Immunol. 1994 Nov;41(3):193-200. doi: 10.1016/0198-8859(94)90036-1.
We investigated the minimal requirements for stimulation of an antigen-specific HLA-DR(alpha, beta 10402)-restricted T-cell clone (Een217) by using transfectants expressing mutant DR beta chains as APCs. Antigen-specific stimulation of Een217 was induced with transfectants expressing DR(alpha, beta 10402) and DR(alpha, beta 1*0403) but not other DR4 subtypes that also bind the peptide recognized by this clone. Analysis of the effects of single amino acid substitutions in the beta chains of each of the DR4 subtypes revealed a requirement for acidic residues in the third HVR, particularly amino acid 71, in stimulation of clone Een217. Functional class II mutants were generated from nonstimulatory DR4 subtype beta chains by acidic residue substitutions within the third HVR. These data define the requirement for negatively charged residues in this region for peptide-induced stimulation of this T-cell clone. The required acidic residues can be located at either position 70, 71, or 74 in the DR beta chain. The negative charge in this segment of the DR beta chain alpha-helix may be required for direct interactions with the T-cell receptor of Een217 or may affect peptide conformation.
我们通过使用表达突变型DRβ链的转染细胞作为抗原呈递细胞（APC），研究了刺激抗原特异性HLA - DR（α，β10402）限制性T细胞克隆（Een217）的最低要求。表达DR（α，β10402）和DR（α，β1*0403）的转染细胞可诱导Een217的抗原特异性刺激，但其他也结合该克隆所识别肽段的DR4亚型则不能。对每个DR4亚型β链中单个氨基酸取代效应的分析表明，刺激克隆Een217需要在第三个高变区（HVR）有酸性残基，特别是氨基酸71。通过在第三个HVR内进行酸性残基取代，从无刺激作用的DR4亚型β链产生了功能性II类突变体。这些数据确定了该区域带负电荷残基对于该T细胞克隆肽诱导刺激的必要性。所需的酸性残基可位于DRβ链的70、71或74位。DRβ链α螺旋这一段的负电荷可能是与Een217的T细胞受体直接相互作用所必需的，或者可能影响肽的构象。
