WordNet

inexperienced
marked by or showing unaffected simplicity and lack of guile or worldly experience; "a teenagers naive ignorance of life"; "the naive assumption that things can only get better"; "this naive simple creature with wide friendly eyes so eager to believe appearances" (同)naif
small room in which a monk or nun lives (同)cubicle
a device that delivers an electric current as the result of a chemical reaction (同)electric cell
a room where a prisoner is kept (同)jail cell, prison cell
(biology) the basic structural and functional unit of all organisms; they may exist as independent units of life (as in monads) or may form colonies or tissues as in higher plants and animals
any small compartment; "the cells of a honeycomb"
a small unit serving as part of or as the nucleus of a larger political movement (同)cadre
the 20th letter of the Roman alphabet (同)t
a tough youth of 1950s and 1960s wearing Edwardian style clothes (同)Teddy boy

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(若き・経験不足から)〈人・言葉などが〉無邪気な,天真らんまんな,世間知らずな / 人を信じやすい,だまされやすい　日本語で「繊細な」という意味で「ナイーブ」使われることがありますが、英語では「ナイーブ」にそのようなニュアンスは含まれません。
(刑務所の)『独房』;(修道院の)小さい独居室 / (ミツバチの)みつ房,巣穴 / 小さい部屋 / 『細胞』 / 電池 / 花粉室 / (共産党などの)細胞
tritiumの化学記号

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/06/15 21:48:53」(JST)

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A naïve T cell is a T cell that has differentiated in bone marrow, and successfully undergone the positive and negative processes of central selection in the thymus. Among these are the naive forms of helper T cells (CD4+) and cytotoxic T cells (CD8+). A naive T cell is considered mature and unlike activated T cells or memory T cells it has not encountered its cognate antigen within the periphery.

Phenotype

Naive T cells are commonly characterized by the surface expression of L-selectin (CD62L); the absence of the activation markers CD25, CD44 or CD69; and the absence of memory CD45RO isoform.^[1] They also express functional IL-7 receptors, consisting of subunits IL-7 receptor-α, CD127, and common-γ chain, CD132. In the naive state, T cells are thought to be quiescent and non-dividing, requiring the common-gamma chain cytokines IL-7 and IL-15 for homeostatic survival mechanisms.^{[citation needed]}

Function

Naive T cells can respond to novel pathogens that the immune system has not yet encountered. Recognition by a naive T cell clone of its cognate antigen results in the initiation of an immune response. In turn, this results in the T cell acquiring an activated phenotype seen by the up-regulation of surface markers CD25⁺, CD44⁺, CD62L^low, CD69⁺ and may further differentiate into a memory T cell.

Having adequate numbers of naive T cells is essential for the immune system to continuously respond to unfamiliar pathogens.

Mechanism of activation

When a recognized antigen binds to the T cell antigen receptor (TCR) located in the cell membrane of Th0 cells, these cells are activated through the following "classical" signal transduction cascade:^[2]

the tyrosine kinase Lck is activated, which results in phosphorylation of
the CD3 coreceptor complex and ζ-chains of the TCR and activation of the ζ-chain- associated protein Zap70
activated Zap70 in turn phosphorylates the membrane adaptor Lat, which subsequently recruits several Src homology domain–containing proteins, including phospholipase C-γ1 (PLC-γ1)
activation of PLC-γ1 results in the hydrolysis of phosphatidylinositol 4,5-bisphosphate to inositol 3,4,5-triphosphate and diacylglycerol
inositol 3,4,5-triphosphate triggers release of Ca²⁺ from intracellular stores and diacylglycerol activates protein kinase C and RasGRP
RasGRP in turn activates the mitogen-activated protein kinase cascade which

An alternative "non-classical" pathway involves activated Zap70 directly phosphorylating the p38 MAPK that in turn induces the expression of the vitamin D receptor (VDR). Furthermore, the expression of PLC-γ1 is dependent on VDR activated by calcitriol.^[2] Naive T cells have very low expression of VDR and PLC-γ1. However activated TCR signaling through p38 upregulates VDR expression and calcitriol activated VDR in turn upregulates PLC-γ1 expression. Hence the activation of naive T cells is crucially dependent on adequate calcitriol levels.^[2]

In summary, activation of T cells first requires activation through the non-classical pathway to increase expression of VDR and PLC-γ1 before activation through the classical pathway can proceed. This provides a delayed response mechanism where the innate immune system is allowed time (~48 hrs) to clear an infection before the inflammatory T cell mediated adaptive immune response kicks in.^[2]

References

^ De Rosa SC, Herzenberg LA, Herzenberg LA, Roederer M (February 2001). "11-color, 13-parameter flow cytometry: identification of human naive T cells by phenotype, function, and T-cell receptor diversity". Nat. Med. 7 (2): 245–8. doi:10.1038/84701. PMID 11175858.
^ ^a ^b ^c ^d von Essen MR, Kongsbak M, Schjerling P, Olgaard K, Odum N, Geisler C (April 2010). "Vitamin D controls T cell antigen receptor signaling and activation of human T cells" (PDF). Nat. Immunol. 11 (4): 344–9. doi:10.1038/ni.1851. PMID 20208539.

UpToDate Contents

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1. BおよびTリンパ球の正常な発生 normal b and t lymphocyte development
2. T細胞受容体シグナル伝達 t cell receptor signaling
3. 関節リウマチのT細胞標的療法 t cell targeted therapies for rheumatoid arthritis
4. 適応細胞性免疫応答 the adaptive cellular immune response
5. ヘルパーT細胞サブセット：疾患における分化および役割 t helper subsets differentiation and role in disease

English Journal

Fms-like tyrosine kinase 3 ligand-dependent dendritic cells in autoimmune inflammation.

Ramos MI, Tak PP, Lebre MC.SourceDepartment of Clinical Immunology and Rheumatology, Academic Medical Center/University of Amsterdam, Amsterdam, The Netherlands; Department of Experimental Immunology, Academic Medical Center/University of Amsterdam, Amsterdam, The Netherlands.
Autoimmunity reviews.Autoimmun Rev.2014 Feb;13(2):117-24. doi: 10.1016/j.autrev.2013.09.010. Epub 2013 Oct 7.
Dendritic cells (DCs) are specialized in capture, processing and presentation of antigens to T cells. Depending on the type of DC and its activation state, the interaction of DCs with naive T cells can lead to different types of immune response, or to T-cell tolerance. The existence of many speciali
PMID 24113138

Modulating the co-stimulatory signal for T cell activation in rheumatoid arthritis: Could it be the first step of the treatment?

Caporali R, Bugatti S, Cavagna L, Antivalle M, Sarzi-Puttini P.SourceDivision of Rheumatology, University of Pavia, IRCCS Policlinico S. Matteo Foundation, Pavia, Italy. Electronic address: caporali@smatteo.pv.it.
Autoimmunity reviews.Autoimmun Rev.2014 Jan;13(1):49-53. doi: 10.1016/j.autrev.2013.06.008. Epub 2013 Jun 15.
Advances in our understanding of the key mediators of chronic inflammation and tissue damage in rheumatoid arthritis (RA) have fostered the development of targeted therapies and greatly expanded the available treatment options. Abatacept, a soluble human fusion protein that selectively modulates the
PMID 23777823

Influenza infection results in local expansion of memory CD8(+) T cells with antigen non-specific phenotype and function.

Sckisel GD, Tietze JK, Zamora AE, Hsiao HH, Priest SO, Wilkins DE, Lanier LL, Blazar BR, Baumgarth N, Murphy WJ.SourceDepartment of Dermatology, School of Medicine, University of California, Davis, Sacramento, CA, USA; Graduate Group in Immunology, University of California, Davis, Davis, CA, USA.
Clinical and experimental immunology.Clin Exp Immunol.2014 Jan;175(1):79-91. doi: 10.1111/cei.12186.
Primary viral infections induce activation of CD8(+) T cells responsible for effective resistance. We sought to characterize the nature of the CD8(+) T cell expansion observed after primary viral infection with influenza. Infection of naive mice with different strains of influenza resulted in the ra
PMID 23937663

Japanese Journal

Differential Expression of ETS Family Transcription Factors in NCCIT Human Embryonic Carcinoma Cells upon Retinoic Acid-Induced Differentiation

Park Sung-Won,Do Hyun-Jin,Ha Woo Tae,Han Mi-Hee,Song Hyuk,Uhm Sang-Jun,Chung Hak-Jae,Kim Jae-Hwan
Biological and Pharmaceutical Bulletin 37(4), 659-665, 2014
… To identify critical ETS factor(s) in germ cell-derived cancer cells, we examined the expression patterns of the 27 ETS transcription factors in naive and differentiated NCCIT human embryonic carcinoma cells, which exhibit both pluripotent and tumorigenic characteristics. … PEA3 increased the proportion of cells in S-phase and promoted cell growth, whereas ESE-1 reduced proliferation potential. …
NAID 130003390972

〈Originals〉Establishment and characterization of mouse T-cell clones reactive to rat xeno-antigens activated via the direct or indirect recognition pathway

Masaki Hideyuki
ACTA MEDICA KINKI UNIVERSITY 38(2), 101-109, 2013-12
… To analyze anti-xeno T-cell responses, xeno-reactive T-cell clones derived from C57BL/6 (B6) mice immunized with Wistar Furth (WF) rat cells were established. … Because all clones are likely to act as effector cells for xenograftrejection, they are expected to be useful for investigating mechanisms of xenograft rejection mediated by cellular immunity, and should be a good source of TcR genes for creating transgenic mice to supply naive xeno-reactive T cells. …
NAID 120005436004

Phase II trial of erlotinib in patients with advanced non-small-cell lung cancer harboring epidermal growth factor receptor mutations: additive analysis of pharmacokinetics

Motoshima Kohei,Nakamura Yoichi,Sano Kazumi,Ikegami Yoji,Ikeda Takaya,Mizoguchi Kosuke,Takemoto Shinnosuke,Fukuda Minoru,Nagashima Seiji,Iida Tetsuya,Tsukamoto Kazuhiro,Kohno Shigeru
Cancer Chemotherapy and Pharmacology 72(6), 1299-1304, 2013-12
… Background: We conducted a phase II trial of erlotinib in patients with advanced non-small-cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) mutations and evaluated the relationship between plasma concentration and efficacy of erlotinib. … Methods: Patients who were previously treated but naive to epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs), with advanced NSCLC harboring EGFR mutations, were enrolled. …
NAID 120005367575