Szewczuk Z, Wieczorek Z, Stefanowicz P, Wilczyński A, Siemion I Z
Faculty of Chemistry, University of Wrocław, Poland.
Arch Immunol Ther Exp (Warsz). 1997;45(4):335-41.
Recently we showed that the fragments of HLA-DQ with the Thr-Pro-Gln-Arg-Gly-Asp-Val-Tyr-Thr and Gln-Arg-Gly-Asp-Val-Tyr-Thr sequences strongly suppress the immune response, while their shorter analogs, Arg-Gly-Asp-Val, Arg-Gly-Asp-Val-Tyr and Gln-Arg-Gly-Asp-Val-Tyr, show very weak stimulatory activity with respect to humoral immunological response. The fragments contain the sequence which is very similar to thymopentin (pentapeptide Arg-Lys-Asp-Val-Tyr, an active fragment (32-36) of thymopoietin, an immune system activator produced in thymi), and at the same time contains the Arg-Gly-Asp (RGD) sequence, known as an inhibitor of adhesion processes. In the present study we found that a hexapeptide: Arg-Gly-Asp-Val-Tyr-Thr is the smallest size fragment of HLA-DQ having both cellular and humoral immunosuppressive activity. We also found that linear and cyclic fragments of HLA-DQ do not affect cell line production of various cytokines, what suggests that the mechanism of interactions of these peptides with the immunological system is different as compared with most other known immunosuppressors.
最近我们发现，具有苏氨酸-脯氨酸-谷氨酰胺-精氨酸-甘氨酸-天冬氨酸-缬氨酸-酪氨酸-苏氨酸和谷氨酰胺-精氨酸-甘氨酸-天冬氨酸-缬氨酸-酪氨酸序列的HLA-DQ片段能强烈抑制免疫反应，而它们较短的类似物，如精氨酸-甘氨酸-天冬氨酸-缬氨酸、精氨酸-甘氨酸-天冬氨酸-缬氨酸-酪氨酸和谷氨酰胺-精氨酸-甘氨酸-天冬氨酸-缬氨酸-酪氨酸，对体液免疫反应的刺激活性非常弱。这些片段包含与胸腺五肽（五肽精氨酸-赖氨酸-天冬氨酸-缬氨酸-酪氨酸，胸腺生成素的活性片段（32-36），胸腺中产生的一种免疫系统激活剂）非常相似的序列，同时还包含被称为黏附过程抑制剂的精氨酸-甘氨酸-天冬氨酸（RGD）序列。在本研究中，我们发现一种六肽：精氨酸-甘氨酸-天冬氨酸-缬氨酸-酪氨酸-苏氨酸是具有细胞和体液免疫抑制活性的最小尺寸的HLA-DQ片段。我们还发现，HLA-DQ的线性和环状片段不会影响细胞系产生各种细胞因子，这表明与大多数其他已知的免疫抑制剂相比，这些肽与免疫系统相互作用的机制有所不同。
