Hayden M S, Grosmaire L S, Norris N A, Gilliland L K, Winberg G, Tritschler D, Tsu T T, Linsley P S, Mittler R S, Senter P D, Fell H P, Ledbetter J A
Bristol-Myers Squibb Pharmaceutical Research Institute, Seattle, Washington, USA.
Tissue Antigens. 1996 Oct;48(4 Pt 1):242-54. doi: 10.1111/j.1399-0039.1996.tb02642.x.
Interaction of the CD80 (B7-1) and CD86 (B7-2) molecules on antigen presenting cells with the receptors CD28 and CTLA-4 on T cells generates signals important in the regulation of immune responses. Because this receptor system involves multiple receptor-ligand interactions, determining the function for individual receptors has been difficult. One approach is the use of antibodies and their derivatives with singular specificity as substitute ligands to explore the activities of these molecules. We have constructed recombinant mono- and bi-specific sFv molecules specific for the CD28 receptor that are capable of binding and generating costimulatory signals to activate T cells. We demonstrate that these soluble molecules are capable of higher levels of costimulation than soluble CD80Ig at equivalent concentrations. We also constructed artificial adhesion receptors on the cell surface using two different CD28-specific sFvIgs fused to the CD80 cytoplasmic and transmembrane domains. In this report, we compared costimulation by a soluble bispecific (alpha CD28-alpha L6) single chain sFvIg fusion protein to that generated by L6 antigen positive (L6+) H3347 tumor cells transduced with cell surface expressed forms of alpha CD28 sFv's. We show that the bispecific protein can target potent CD28 costimulatory activity to L6+ tumor cells in vitro. We also show that transfection of the cell surface forms of the two different CD28 sFvIgs into H3347 tumor cells allows them to generate significant costimulatory signals to activated T cells. Finally, we demonstrate that tumor cell presentation of either the soluble bispecific or transduced cell surface sFv generate similar costimulatory effects resulting in T cell activation.
抗原呈递细胞上的CD80（B7-1）和CD86（B7-2）分子与T细胞上的CD28和CTLA-4受体相互作用，产生对免疫反应调节很重要的信号。由于该受体系统涉及多种受体-配体相互作用，确定单个受体的功能一直很困难。一种方法是使用具有单一特异性的抗体及其衍生物作为替代配体来探索这些分子的活性。我们构建了对CD28受体具有特异性的重组单特异性和双特异性sFv分子，它们能够结合并产生共刺激信号以激活T细胞。我们证明，在等效浓度下，这些可溶性分子比可溶性CD80Ig具有更高水平的共刺激作用。我们还使用与CD80细胞质和跨膜结构域融合的两种不同的CD28特异性sFvIg在细胞表面构建了人工粘附受体。在本报告中，我们比较了可溶性双特异性（αCD28-αL6）单链sFvIg融合蛋白与用αCD28 sFv的细胞表面表达形式转导的L6抗原阳性（L6 +）H3347肿瘤细胞产生的共刺激作用。我们表明，双特异性蛋白可以在体外将有效的CD28共刺激活性靶向L6 +肿瘤细胞。我们还表明，将两种不同的CD28 sFvIg的细胞表面形式转染到H3347肿瘤细胞中，使它们能够向活化的T细胞产生显著的共刺激信号。最后，我们证明可溶性双特异性或转导的细胞表面sFv的肿瘤细胞呈递产生相似的共刺激作用，从而导致T细胞活化。
