Martinez-Valdez Hector, Madrid-Marina Vicente, Cohen Amos
Department of Immunology, Box 178, The University of Texas MD Anderson Cancer Center, USA.
BMC Immunol. 2002;3:1. doi: 10.1186/1471-2172-3-1. Epub 2002 Jan 18.
Intrathymic development and selection of the T lymphocyte repertoire is restricted by the interactions of the T cell antigen receptor and CD4 or CD8 co-receptors with self major histocompatibility complex molecules. Positive or negative selection depends on a tight regulatory control of CD4 and CD8 expression. Determining the intracellular signals that differentially regulate the expression of CD4 and CD8 is important to understand the mechanisms that are implicated in selection of single positive CD4+CD8- or CD4-CD8+.
The present study shows that stimulation of human thymocytes by phorbol esters or cAMP result in a differential regulation of CD4 and CD8 expression, both at the mRNA and cell surface glycoprotein level.
The differential regulation of CD4 and CD8 gene expression suggests that the selective activation of protein kinase C (PKC) and cAMP-dependent protein kinases (PKA) may be required for the selection of single positive CD4+CD8- and CD4-CD8+ cells during Intrathymic differentiation.
胸腺内T淋巴细胞库的发育和选择受到T细胞抗原受体以及CD4或CD8共受体与自身主要组织相容性复合体分子相互作用的限制。阳性或阴性选择取决于对CD4和CD8表达的严格调控。确定差异调节CD4和CD8表达的细胞内信号对于理解参与单阳性CD4+CD8-或CD4-CD8+选择的机制很重要。
本研究表明，佛波酯或cAMP刺激人胸腺细胞会导致CD4和CD8表达在mRNA和细胞表面糖蛋白水平上的差异调节。
CD4和CD8基因表达的差异调节表明，在胸腺内分化过程中，选择单阳性CD4+CD8-和CD4-CD8+细胞可能需要蛋白激酶C（PKC）和cAMP依赖性蛋白激酶（PKA）的选择性激活。
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