Davis L S, Oppenheimer-Marks N, Bednarczyk J L, McIntyre B W, Lipsky P E
Harold C. Simmons Arthritis Research Center, University of Texas Southwestern Medical Center, Dallas 75235.
J Immunol. 1990 Aug 1;145(3):785-93.
The capacity of purified fibronectin to costimulate human T cell DNA synthesis was examined. Low concentrations of immobilized fibronectin, but not soluble fibronectin, augmented anti-CD3-induced proliferation of highly purified human T cells. In the absence of anti-CD3 stimulation, immobilized fibronectin did not induce T cell proliferation alone or in the presence of IL-2 or phorbol dibutyrate. Although fibronectin is present in high concentrations in the serum, immobilized fibronectin was able to costimulate T cell proliferation when cells were cultured in serum-containing medium. Immobilized collagen type I did not enhance anti-CD3 stimulated T cell responses, whereas gelatin (denatured collagen) and laminin were able to enhance anti-CD3 stimulated T cell responses modestly. The effects of gelatin, however, appeared to be indirect, because it could not enhance responses in medium devoid of fibronectin. Immobilized fibronectin enhanced anti-CD3 induced proliferation of both CD45RA dim and CD45RA bright subsets within both the CD4+ and CD8+ subpopulations of T cells, although cells with the CD45RA dim phenotype were costimulated by lower concentrations of immobilized fibronectin. Enhancement of anti-CD3 induced proliferation by immobilized fibronectin was completely inhibited by a mAb to CD29, the integrin beta 1-chain (4B4) and not by a variety of other mAb. In contrast to its effects on proliferation, 4B4 only partially blocked T cell binding to anti-CD3 and fibronectin-coated macrowells. These findings suggested that the interaction between fibronectin and its receptor transduced a signal to the T cell and did not merely stabilize the interaction between anti-CD3 and the CD3 complex. Further experiments confirmed this observation. Thus fibronectin could enhance anti-CD3 responses when it was immobilized to a separate surface. The augmentation of anti-CD3 stimulated proliferation induced by immobilized fibronectin was also inhibited partially by mAb to either VLA-4 or VLA-5 and completely by a combination of the two mAb. The mAb to VLA-4 not only blocked the capacity of immobilized fibronectin to enhance anti-CD3-induced T cell proliferation but also directly costimulated T cell responses. Thus, at least two fibronectin receptors are involved in fibronectin-mediated costimulation of T cell proliferation. These studies indicate that signals are transduced through the fibronectin receptors, VLA-4 and VLA-5, that augment T cell responses and therefore implicate the extracellular matrix protein fibronectin as an important influence regulating T cell responsiveness in vivo.
研究了纯化的纤连蛋白共刺激人T细胞DNA合成的能力。低浓度的固定化纤连蛋白而非可溶性纤连蛋白可增强抗CD3诱导的高度纯化的人T细胞增殖。在没有抗CD3刺激的情况下，固定化纤连蛋白单独或在存在IL-2或佛波酯丁酸盐时均不诱导T细胞增殖。尽管血清中纤连蛋白浓度很高，但当细胞在含血清的培养基中培养时，固定化纤连蛋白仍能够共刺激T细胞增殖。固定化的I型胶原不能增强抗CD3刺激的T细胞反应，而明胶（变性胶原）和层粘连蛋白能够适度增强抗CD3刺激的T细胞反应。然而，明胶的作用似乎是间接的，因为它不能在缺乏纤连蛋白的培养基中增强反应。固定化纤连蛋白增强了抗CD3诱导的T细胞CD4+和CD8+亚群中CD45RA dim和CD45RA bright亚群的增殖，尽管具有CD45RA dim表型的细胞被较低浓度的固定化纤连蛋白共刺激。固定化纤连蛋白增强抗CD3诱导的增殖完全被针对CD29（整合素β1链，4B4）的单克隆抗体抑制，而不被多种其他单克隆抗体抑制。与其对增殖的影响相反，4B4仅部分阻断T细胞与抗CD3和纤连蛋白包被的微孔的结合。这些发现表明纤连蛋白与其受体之间的相互作用向T细胞转导了信号，而不仅仅是稳定抗CD3与CD3复合物之间的相互作用。进一步的实验证实了这一观察结果。因此，当纤连蛋白固定在单独的表面时，它可以增强抗CD3反应。固定化纤连蛋白诱导的抗CD3刺激的增殖增强也被针对VLA-4或VLA-5的单克隆抗体部分抑制，并被这两种单克隆抗体的组合完全抑制。针对VLA-4的单克隆抗体不仅阻断了固定化纤连蛋白增强抗CD3诱导的T细胞增殖的能力，而且直接共刺激T细胞反应。因此，至少两种纤连蛋白受体参与了纤连蛋白介导的T细胞增殖共刺激。这些研究表明，信号通过纤连蛋白受体VLA-4和VLA-5转导，增强了T细胞反应，因此表明细胞外基质蛋白纤连蛋白是体内调节T细胞反应性的重要因素。
