Zang Xingxing, Loke P'ng, Kim Jayon, Murphy Kenneth, Waitz Rebecca, Allison James P
Howard Hughes Medical Institute, Department of Molecular and Cell Biology, Cancer Research Laboratory, University of California, Berkeley, CA 94720, USA.
Proc Natl Acad Sci U S A. 2003 Sep 2;100(18):10388-92. doi: 10.1073/pnas.1434299100. Epub 2003 Aug 14.
B7 family proteins provide costimulatory signals that regulate T cell responses. Here we report the third set of B7 family-related T cell inhibitory molecules with the identification of a homolog of the B7 family, B7x. It is expressed in immune cells, nonlymphoid tissues, and some tumor cell lines. B7x inhibits cell-cycle progression, proliferation, and cytokine production of both CD4+ and CD8+ T cells. B7x binds a receptor that is expressed on activated, but not resting T cells that is distinct from known CD28 family members. Its receptor may be a recently identified inhibitory molecule, B and T lymphocyte attenuator. These studies identify a costimulatory pathway that may have a unique function in downregulation of tissue-specific autoimmunity and antitumor responses.
B7家族蛋白提供共刺激信号，调节T细胞反应。在此，我们报告了第三组与B7家族相关的T细胞抑制分子，鉴定出了B7家族的一个同源物B7x。它在免疫细胞、非淋巴组织和一些肿瘤细胞系中表达。B7x抑制CD4⁺和CD8⁺ T细胞的细胞周期进程、增殖及细胞因子产生。B7x与一种在活化的而非静止的T细胞上表达的受体结合，该受体不同于已知的CD28家族成员。其受体可能是最近鉴定出的一种抑制性分子——B和T淋巴细胞衰减因子。这些研究确定了一条共刺激途径，该途径可能在下调组织特异性自身免疫和抗肿瘤反应中具有独特作用。
