Szewczuk Z, Siemion I Z, Wieczorek Z
Department of Chemistry, University of Wroclaw, Poland.
Mol Immunol. 1996 Aug;33(11-12):903-8. doi: 10.1016/s0161-5890(96)00059-4.
Class II human leukocyte antigens (HLA-II) are cell surface alpha beta heterodimers (M(r) approximately 60,000) that play a pivotal role in the immune response by presenting peptides derived from environmental antigens to the T-cell receptor. A 167-171 fragment of the beta 2-chain of the HLA-DQ molecule consists of the sequence RGDVY, which is very similar to thymopentin (pentapeptide RKDVY, an active fragment (32-36) of thymopoietin, an immune system activator produced in thymi), and at the same time contains the RGD sequence, known as an inhibitor of adhesion processes. We synthesized and investigated the immunomodulatory activity of series of peptide fragments of HLA-DQ containing thymopentin-like sequences. The results indicate that all synthesized peptides suppress the cellular immune response. However, RGDV, RGDVY and QRGDVY show very weak stimulatory activity in humoral immunological response tests. In contrast to the shorter peptides, the nonapeptide fragment of HLA-DQ, TPQRGDVYT, shows significant immunosuppressive activity in all tests. A possible role of these fragments of the polypeptide chain of HLA-DQ in the regulation of HLA functions is discussed.
II类人类白细胞抗原（HLA-II）是细胞表面的αβ异二聚体（分子量约60,000），通过将源自环境抗原的肽呈递给T细胞受体，在免疫反应中起关键作用。HLA-DQ分子β2链的167 - 171片段由序列RGDVY组成，该序列与胸腺五肽（五肽RKDVY，胸腺生成素的活性片段（32 - 36），胸腺生成的一种免疫系统激活剂）非常相似，同时包含RGD序列，已知其为黏附过程的抑制剂。我们合成并研究了一系列含有胸腺五肽样序列的HLA-DQ肽片段的免疫调节活性。结果表明，所有合成肽均抑制细胞免疫反应。然而，RGDV、RGDVY和QRGDVY在体液免疫反应测试中显示出非常弱的刺激活性。与较短的肽相反，HLA-DQ的九肽片段TPQRGDVYT在所有测试中均显示出显著的免疫抑制活性。讨论了HLA-DQ多肽链这些片段在HLA功能调节中的可能作用。
