Characterization Of Cell Surface Molecules Important For

本研究的目的是确定调节人幼稚T细胞活化的因素;特别是我们对NKG 2D活化和LAIR-1抑制性受体所起的作用感兴趣。在人类中，所有CD 8 + T细胞均表达NKG 2D，但在小鼠中，仅由活化和记忆CD 8 + T细胞表达。我们纯化了人初始CD 8 + T细胞，以表明NKG 2D作为TCR诱导的Ca 2+动员和增殖的共刺激受体。产生的效应细胞偏向1型表型，并产生高水平的IFN-和TNF-。NKG 2D配体、MHC I类链相关（MIC）A、MICB和UL 16结合蛋白在增殖细胞上表达，NKG 2D下调。向培养基中添加稳态细胞因子IL-7和IL-15不仅增强了增殖，而且抵消了NKG 2D的下调，比添加IL-2更明显。这些结果表明，NKG 2D可以调节人初始CD 8 + T细胞的启动，这可能为增强和引导免疫应答提供了替代机制。 人白细胞相关免疫球蛋白样受体-1（LAIR-1）是一种跨膜糖蛋白，具有单一的细胞外免疫球蛋白样结构域和含有两个免疫受体酪氨酸抑制基序（ITIM）的胞质尾区。它在大多数人单核白细胞上组成型表达，并作为抑制性受体发挥作用。在这项研究中，我们表明，新鲜分离的外周血T细胞是异质性的LAIR-1的表达水平。我们已经发现，幼稚T细胞表达最高水平的LAIR-1，甚至超过记忆细胞。LAIR-1的交联抑制新鲜分离的人初始T细胞和整个CD 4+或CD 8 + T细胞群体中的T细胞受体（TCR）介导的信号。TCR交联在需要p38 MAP激酶和ERK信号传导的过程中增加LAIR-1的细胞表面表达。总之，这些结果表明LAIR-1能够负调节T细胞功能，并且其通过初始T细胞的高水平表达表明其可能在免疫应答发展的早期阶段起作用。

The purpose of this research is to determine factors that regulate the activation of human naive T cells; in particular we are interested in the roles played by the NKG2D activation and LAIR-1 inhibitory receptors. In humans, all CD8+ T cells express NKG2D, but in mouse, it is only expressed by activated and memory CD8+ T cells. We purified human naive CD8+ T cells to show that NKG2D serves as a costimulatory receptor for TCR induced Ca2+ mobilization and proliferation. The resulting effector cells are skewed toward a type 1 phenotype and produce high levels of IFN- and TNF-. NKG2D ligands, MHC class I chain-related (MIC)A, MICB, and UL16-binding proteins are expressed on the proliferating cells and NKG2D is down-regulated. The addition of the homeostatic cytokines IL-7 and IL-15 to the culture medium not only enhances proliferation but also counteracts the down-regulation of NKG2D, more so than the addition of IL-2. These results indicate that NKG2D can regulate the priming of human naive CD8+ T cells, which may provide an alternative mechanism for potentiating and channeling the immune response. Human leukocyte-associated Ig-like receptor-1 (LAIR-1) is a transmembrane glycoprotein with a single extracellular Ig-like domain and a cytoplasmic tail containing two immunoreceptor tyrosine-based inhibition motifs (ITIMs). It is constitutively expressed on the majority of human mononuclear leukocytes and functions as an inhibitory receptor. In this study, we show that freshly isolated peripheral blood T cells are heterogeneous in their expression levels of LAIR-1. We have found that naive T cells express the highest levels of LAIR-1, even more than memory cells. The cross-linking of LAIR-1 inhibits T cell receptor (TCR) mediated signals in freshly isolated human naive T cells and whole populations of CD4+ or CD8+ T cells. TCR cross-linking increased cell surface expression of LAIR-1 in a process that requires p38 MAP kinase and ERK signaling. Altogether, these results indicate that LAIR-1 is capable of negatively regulating T cell functions, and its high level of expression by naive T cells suggests that it may function at an early stage in the development of an immune response.