Arai T, Yoshida K, Kaburaki J, Inoko H, Ikeda Y, Kawakami Y, Kuwana M
Institute for Advanced Medical Research and Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan.
Blood. 2001 Sep 15;98(6):1889-96. doi: 10.1182/blood.v98.6.1889.
Autoreactive CD4(+) T cells to beta2-glycoprotein I (beta2GPI) that promote antiphospholipid antibody production were recently identified in patients with antiphospholipid syndrome (APS). To further examine antigen recognition profiles and T-cell helper activity in beta2GPI-reactive T cells, 14 CD4(+) T-cell clones specific to beta2GPI were generated from 3 patients with APS by repeated stimulation of peripheral blood T cells with recombinant beta2GPI. At least 4 distinct T-cell epitopes were identified, but the majority of the beta2GPI-specific T-cell clones responded to a peptide encompassing amino acid residues 276 to 290 of beta2GPI (KVSFFCKNKEKKCSY; single-letter amino acid codes) that contains the major phospholipid-binding site in the context of the DRB4*0103 allele. Ten of 12 beta2GPI-specific T-cell clones were able to stimulate autologous peripheral blood B cells to promote anti-beta2GPI antibody production in the presence of recombinant beta2GPI. T-cell helper activity was exclusively found in T-cell clones capable of producing interleukin 6 (IL-6). In vitro anti-beta2GPI antibody production induced by T-cell clones was inhibited by anti-IL-6 or anti-CD40 ligand monoclonal antibody. In addition, exogenous IL-6 augmented anti-beta2GPI antibody production in cultures of the T-cell clone lacking IL-6 expression. These results indicate that beta2GPI-specific CD4(+) T cells in patients with APS preferentially recognize the antigenic peptide containing the major phospholipid-binding site and have the capacity to stimulate B cells to produce anti-beta2GPI antibodies through IL-6 expression and CD40-CD40 ligand engagement. These findings are potentially useful for clarifying the pathogenesis of APS and for developing therapeutic strategies that suppress pathogenic antiphospholipid antibody production in these patients.
最近在抗磷脂综合征（APS）患者中发现了针对β2糖蛋白I（β2GPI）的自身反应性CD4（+）T细胞，其可促进抗磷脂抗体的产生。为了进一步研究β2GPI反应性T细胞中的抗原识别谱和T细胞辅助活性，通过用重组β2GPI反复刺激3例APS患者的外周血T细胞，产生了14个针对β2GPI的CD4（+）T细胞克隆。鉴定出至少4个不同的T细胞表位，但大多数β2GPI特异性T细胞克隆对包含β2GPI第276至290位氨基酸残基的肽（KVSFFCKNKEKKCSY；单字母氨基酸代码）有反应，该肽在DRB4*0103等位基因背景下包含主要的磷脂结合位点。12个β2GPI特异性T细胞克隆中有10个能够在重组β2GPI存在的情况下刺激自体外周血B细胞以促进抗β2GPI抗体的产生。T细胞辅助活性仅在能够产生白细胞介素6（IL-6）的T细胞克隆中发现。T细胞克隆诱导的体外抗β2GPI抗体产生受到抗IL-6或抗CD40配体单克隆抗体的抑制。此外，外源性IL-6增强了缺乏IL-6表达的T细胞克隆培养物中的抗β2GPI抗体产生。这些结果表明，APS患者中β2GPI特异性CD4（+）T细胞优先识别包含主要磷脂结合位点的抗原肽，并具有通过IL-6表达和CD40-CD40配体结合刺激B细胞产生抗β2GPI抗体的能力。这些发现可能有助于阐明APS的发病机制，并有助于制定抑制这些患者中致病性抗磷脂抗体产生的治疗策略。
