【摘要】 ＬＦＡ－１和ＩＣＡＭ－１广泛表达于各胸腺细胞亚群，但ＩＣＡＭ－１在ＰＮＡ￣＋细胞的表达下调。本文报道：用抗ＬＦＡ－１／ＩＣＡＭ－１和抗ＣＤ３单抗，分析了粘附分子ＬＦＡ－１／ＩＣＡＭ－１对抗ＣＤ３诱导的胸腺细胞［Ｃａ￣（２＋）］ｉ应答的影响。结果显示，可溶性抗ＬＦＡ－１／ＩＣＡＭ－１可抑制ＣｏｎＡ刺激的胸腺细胞增殖，且以抗ＬＦＡ－１抗体的作用更为显著，在ＣｏｎＡ或抗ＣＤ３诱导的胸腺细胞［Ｃａ￣（２＋）］ｉ应答中，抗ＬＦＡ－１单抗可明显抑制［Ｃａ￣（２＋）ｉ升高。但如果用二抗交联ＣＤ３和ＬＦＡ－１，胸腺细胞［Ｃａ￣（２＋）ｉ则显著高于单独交联ＣＤ３时的水平（Ｐ＜０．０１），而ＣＤ３与ＩＣＡＭ－ｌ交联却无此效应，此外，仅交联ＬＦＡ－１或ＩＣＡＭ－１也无诱导［Ｃａ￣（２＋）］ｉ应答的作用。提示在ＬＦＡ－ｌ与ＩＣＡＭ－１介导的胸腺细胞与胸腺基质细胞相互作用中，ＬＦＡ－１可为ＴＣＲ／ＣＤ３途径介导的胸腺细胞活化提供复合刺激信号。更多还原

【Abstract】 ymphocyte function-associated antigen(LFA-1)and its ligand intercellular adhesion molecule-l(ICAM-1)were expressed on each thymocyte subpopulation, but the expression of ICAM-1on the PNA+ subset was down-regulated.The early signaling events involved in the activation of thymocytes were analyzed by[Ca2+]i(intercellu-lar free calcium concentration)response of thymocytes triggered by anti-CD3 antibody to determine the contribu-tion by the LFA-1/ICAM-1interaction. Thc results showed that soluble anti-LFA-1or anti-ICAM-1antibodies could inhibit the proliferation of thymocytes upon Con A stimulation ,and the inhibitory effect of anti-LFA-1 was more significant than anti-ICAM-1. When anti-LFA-1was added to the Con A-or immobilized anti- CD3-stimulat-ed thymocyte cultures,a remarkable decrease in the intercellular levels of free Ca2+ was observed.However,thecross-linking of CD3 with LFA-1 by secondary antibodies resulted in the elevation in [Ca2+]i, and this increase was m uch higher than that induced by cross-linked CD3 alone (P<0.01 ). But this effect was not exhibited bycross-linking CD3 and ICAM-1.In addition,it was unable to induce[Ca2+]i response in thymocytes by cross-link-ing LFA-1/ICAM-1alone. Thus,thc necessary costimulation required for CD3-mediated proliferation of thymo-cytes in this model system may be provided by the LFA-1/ICAM-l interaction which in combination with anti-CD3 leads to signal-transduction events.更多还原