HLA-DRB1特异性Ⅱ型胶原多肽序列中氨基酸替换对T细胞免疫的影响

The effect of altered CⅡ peptides on HLA-DRB1 restricted T cell responses

目的探讨Ⅱ型胶原(CⅡ)的抗原性多肽CⅡ263～272及其变构肽在T细胞激活中的作用,以筛选可与HLA-DRB1特异性结合,而无或有低T细胞激活作用的CⅡ变构肽,为利用CⅡ变构肽抑制类风湿关节炎(RA)患者的HLA-DRB1限制性T细胞激活提供实验依据.方法采用固相合成法,用丙氨酸和甘氨酸替换CⅡ263～272序列中与T细胞受体结合的氨基酸,并用异硫氰酸荧光素(FITC)标记这些CⅡ变构肽,观察CⅡ变构肽与抗原呈递细胞表面HLA-DR1分子的结合能力;测定与CⅡ263～272或变构肽共孵育HLA-DR1特异性T细胞株上清液中的白细胞介素(IL)-2浓度,研究CⅡ变构肽在T细胞激活中的作用.结果CⅡ变构肽(269A)可与抗原呈递细胞(L57.23)表面的HLA-DR1分子特异性结合;在HLA-DR1特异性T细胞激活系统中,CⅡ263～272在3.1～5.0μg/ml的浓度下,可明显刺激T细胞激活,而CⅡ变构肽267A,268A,sub269～270,sub267～270未出现或仅有轻度T细胞激活作用(P＜0.01或P＜0.05).结论CⅡ263～272含有与HLA-DR1和与T细胞结合的抗原表位,可以刺激CⅡ特异性T细胞增生,替换与T细胞结合的氨基酸后,变构肽仍可与HLA-DR1结合,但对T细胞激活作用减弱或无T细胞激活作用.

Objective To evaluate the effect of altered CⅡ263~272 peptides on T cell activation. Methods CⅡ263~272 with 267Q,268G,269P,270K substituted by A and/or G were synthesized using solid phase techniques.FITC conjugated modified peptide (269A),phycoerythrin (PE) conjugated anti-Human HLA-DR were added to HLA-DR1 APC (L57.23).Expression of FITC and PE stainning were analyzed by fluorescence-activated cell sorting.Irridiated HLA-DR1 expressing APC was incubated with CⅡ 263~272 or various concentrations of the modified peptides for 2 hours before T cell (3.19) were added.Supernatants were harvested and then added to IL-2 dependent CTLL cell.Cell proliferation was examined by MTT method. Results The altered peptide of CⅡ263~272 were able to specifically bind to HLA-DR1 molecule expressed on cell membrane of HLA-DR1 transfected APC.Collagen Ⅱ 263~272, in concentration of 3.1,6.3,12.5,25,50 μg/ml,increased the HLA-DR1 restricted T cell proliferation, while the altered peptide did not or barely stimulate T cell clone, compared to wild type CⅡ263~272 (P<0.01 or P<0.05).Conclusion Substitution of TCR binding residues of CⅡ263~272 inhibites the HLA-DR1 restricted T cell clone.