scholarly journals Defective development of thymocytes overexpressing the costimulatory molecule, heat-stable antigen.

1994 ◽  
Vol 179 (1) ◽  
pp. 177-184 ◽  
Author(s):  
M R Hough ◽  
F Takei ◽  
R K Humphries ◽  
R Kay
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Development ◽  
Costimulatory Molecule ◽  
Cell Development ◽  
Double Negative ◽  
Double Positive ◽  
Heat Stable ◽  
Heat Stable Antigen ◽  
Single Positive

Heat-stable antigen (HSA) is a small, glycosyl phosphatidylinositol-anchored protein that can act as a costimulatory molecule for antigen-dependent activation of helper T cells. In addition to being expressed on antigen-presenting B cells, HSA is also expressed during the initial stages of T cell development in the thymus. HSA levels are very high on immature CD4-, CD8- double negative thymocytes, but are reduced on CD4+, CD8+ double positive cells undergoing selection in the thymus, and are entirely eliminated when these cells differentiate into immunologically competent CD4+ or CD8+ single positive T cells. To examine the potential roles of this molecule in T cell development and selection, we generated transgenic mice in which HSA was highly expressed on all classes of thymocytes. The consequence of deregulated HSA expression was a pronounced reduction in the numbers of double positive and single positive thymocytes, whereas the numbers of their double negative precursors were largely unaffected. These results demonstrate that downregulation of HSA expression at the double positive stage is a critical event in thymocyte development. The depletion of thymocytes resulting from HSA overexpression begins at the same time as the onset of negative selection, suggesting that HSA may provide signals that contribute to determining the efficiency of this process.

Altered thymocyte and T cell development in neonatal mice with hyperoxia-induced lung injury

2018 ◽  
Vol 46 (4) ◽  
pp. 441-449
Author(s):  
Sowmya Angusamy ◽  
Tamer Mansour ◽  
Mohammed Abdulmageed ◽  
Rachel Han ◽  
Brian C. Schutte ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Lung Injury ◽  
T Cell Development ◽  
Adaptive Immune System ◽  
Cell Development ◽  
Thymocyte Development ◽  
Double Positive ◽  
Neonatal Mice ◽  
Single Positive

Abstract Background: The adaptive immune system of neonates is relatively underdeveloped. The thymus is an essential organ for adaptive T cell development and might be affected during the natural course of oxygen induced lung injury. The effect of prolonged hyperoxia on the thymus, thymocyte and T cell development, and its proliferation has not been studied extensively. Methods: Neonatal mice were exposed to 85% oxygen (hyperoxia) or room air (normoxia) up to 28 days. Flow cytometry using surface markers were used to assay for thymocyte development and proliferation. Results: Mice exposed to prolonged hyperoxia had evidence of lung injury associated alveolar simplification, a significantly lower mean weight, smaller thymic size, lower mean thymocyte count and higher percentage of apoptotic thymocytes. T cells subpopulation in the thymus showed a significant reduction in the count and proliferation of double positive and double negative T cells. There was a significant reduction in the count and proliferation of single positive CD4+ and CD8+ T cells. Conclusions: Prolonged hyperoxia in neonatal mice adversely affected thymic size, thymocyte count and altered the distribution of T cells sub-populations. These results are consistent with the hypothesis that prolonged hyperoxia causes defective development of T cells in the thymus.

Heme Metabolic Gene Expression In FLVCR-Knockout Mice During T Cell Development

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2787-2787
Author(s):  
Mary Philip ◽  
Alexandra R. Zaballa ◽  
Blake T. Hovde ◽  
Janis L. Abkowitz
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Development ◽  
Cell Development ◽  
Transcriptional Level ◽  
Mrna Levels ◽  
Double Positive ◽  
Metabolic Gene Expression ◽  
Free Heme ◽  
Single Positive

Abstract Abstract 2787 Heme is essential for nearly every organism and cell. However, free heme can induce free radical formation and cellular damage, therefore cells must carefully regulate heme levels. The feline leukemia virus subgroup C receptor (FLVCR) exports heme from cells. Conditional deletion of Flvcr has been shown to cause progressive anemia in neonatal and adult mice (Science 319:825-8, 2008). Recently, we developed a transplant model in which developing lymphocytes lacked FLVCR while erythroid cells expressed FLVCR, preventing anemia, and found that CD4 and CD8 peripheral T cells were severely decreased while B cell numbers were normal. We further demonstrated that FLVCR-knockout thymocytes were blocked at the CD4CD8 double-positive (DP) stage (Blood [ASH Annual Meeting Abstracts] 114: 913, 2009). We hypothesized that developing T cells lacking FLVCR are arrested at the DP stage because of increased intracellular free heme (IFH). While heme is required for erythroid function, little is known about the role of heme in T cell development. Real-time dynamic quantification of IFH in vivo or from ex vivo tissue is a major challenge in heme biology. We reasoned that by measuring the expression of genes transcriptionally-regulated by heme, we could indirectly assess IFH. Three proteins are key regulators of IFH in non-erythroid cells: aminolevulinic acid synthase-1 (ALAS1) is the rate-limiting enzyme in heme synthesis, FLVCR exports heme, and heme oxygenase-1 (HMOX1) degrades heme. Normal thymic T cell development proceeds from the CD4CD8 double-negative (DN) to the CD4CD8 double-positive (DP) stage, which then go on to either the CD4 single-positive (CD4SP) or CD8 single-positive (CD8SP) stage. We flow-sorted cells from each stage and used multiplex quantitative PCR (qPCR) to determine that all three genes were expressed at higher levels early in normal T cell development during the DN and DP stages and then at lower levels in the CD4SP and CD8SP. Heme binding to the negative regulatory protein BACH1 causes dissociation of BACH1 from the Hmox1 promoter and increased Hmox1 transcription, while expression and stability of Alas1 mRNA is under negative feedback control by heme. Therefore, we predicted that increased IFH in FLVCR-knockout thymocytes would lead to an increase in Hmox1 mRNA and a decrease in Alas1 mRNA levels. We compared expression of heme metabolic genes in FLVCR-knockout and control thymocytes. Flvcr expression was nearly absent in FLVCR-knockout DN and DP cells, however, there was a slight increase in Flvcr expression by the few CD4SP and CD8SP present. To understand this result, we analyzed the extent of genomic Flvcr deletion in FLVCR-knockout thymocytes and peripheral B and T cells by genomic qPCR. DN and DP thymocytes had near complete deletion of Flvcr while CD4SP and CD8SP had slightly less-efficient deletion, likely accounting for the increased Flvcr mRNA levels. Strikingly, Flvcr deletion in the few peripheral T cells present was 50–60% in contrast to peripheral B cells (>90%): only those T cells with incomplete Flvcr deletion survived, further underscoring the absolute requirement for FLVCR in developing T cells. We next examined Hmox1 mRNA expression and found that Hmox1 expression was higher in FLVCR-knockout DP, CD4SP, and CD8SP compared to wild-type FLVCR controls. This supports our hypothesis that FLVCR loss leads to increased IFH during T cell development. Alas1 expression was similar in FLVCR-knockout and control thymocytes, a finding that could be explained because heme regulates ALAS1 activity not only at the transcriptional level but also at the post-transcriptional level. Thus Alas1 expression may not be a good indicator of IFH. In summary, we developed a method to quantify relative free heme levels in developing thymocytes through the measurement of heme metabolic gene expression and found that IFH levels were increased in FLVCR-knockout thymocytes compared to controls. Whether and how excess free heme derails the T cell developmental program, remains to be discovered. Disclosures: No relevant conflicts of interest to declare.

Overlapping functions of human CD3δ and mouse CD3γ in αβ T-cell development revealed in a humanized CD3γ-deficient mouse

Blood ◽  
2006 ◽  
Vol 108 (10) ◽  
pp. 3420-3427 ◽  
Author(s):  
Edgar Fernández-Malavé ◽  
Ninghai Wang ◽  
Manuel Pulgar ◽  
Wolfgang W. A. Schamel ◽  
Balbino Alarcón ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Development ◽  
Cell Development ◽  
Double Negative ◽  
Wild Type ◽  
Thymocyte Development ◽  
Double Positive ◽  
Deficient Mice ◽  
Αβ T Cells

Abstract Humans lacking the CD3γ subunit of the pre-TCR and TCR complexes exhibit a mild αβ T lymphopenia, but have normal T cells. By contrast, CD3γ-deficient mice are almost devoid of mature αβ T cells due to an early block of intrathymic development at the CD4–CD8– double-negative (DN) stage. This suggests that in humans but not in mice, the highly related CD3δ chain replaces CD3γ during αβ T-cell development. To determine whether human CD3δ (hCD3δ) functions in a similar manner in the mouse in the absence of CD3γ, we introduced an hCD3δ transgene in mice that were deficient for both CD3δ and CD3γ, in which thymocyte development is completely arrested at the DN stage. Expression of hCD3δ efficiently supported pre-TCR–mediated progression from the DN to the CD4+CD8+ double-positive (DP) stage. However, αβTCR-mediated positive and negative thymocyte selection was less efficient than in wild-type mice, which correlated with a marked attenuation of TCR-mediated signaling. Of note, murine CD3γ-deficient TCR complexes that had incorporated hCD3δ displayed abnormalities in structural stability resembling those of T cells from CD3γ-deficient humans. Taken together, these data demonstrate that CD3δ and CD3γ play a different role in humans and mice in pre-TCR and TCR function during αβ T-cell development.

scholarly journals A Role for Bcl-2 in Notch1-Dependent Transcription in Thymic Lymphoma Cells

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Ronit Vogt Sionov ◽  
Shlomit Kfir-Erenfeld ◽  
Rachel Spokoini ◽  
Eitan Yefenof
Keyword(s):  
T Cells ◽  
Transcription Factor ◽  
T Cell ◽  
T Cell Development ◽  
Cell Development ◽  
Double Negative ◽  
Double Positive ◽  
Lymphoma Cells ◽  
Thymic Lymphoma ◽  
Induced Apoptosis

Notch1 is a transcription factor important for T-cell development. Notch1 is active in double negative (DN) thymocytes, while being depressed in double positive (DP) thymocytes. Synchronously, the expression of Bcl-2 becomes downregulated during the transition from DN to DP thymocytes. We previously observed that overexpression of an intracellular active Notch1 (ICN) in Bcl-2-positive 2B4 T cells leads to the transcription of Notch1-regulated genes. However, these genes were not induced in Bcl-2-negative DP PD1.6 thymic lymphoma cells overexpressing ICN. Here we show that, when Bcl-2 is simultaneously introduced into these cells, Notch-regulated genes are transcribed. Only in the presence of both Bcl-2 and ICN, PD1.6 thymic lymphoma cells become resistant to glucocorticoid (GC)-induced apoptosis. Our data suggest that Bcl-2 plays a role in modulating Notch1 function in T cells.

scholarly journals The role of the Runx transcription factors in thymocyte differentiation and in homeostasis of naive T cells

2007 ◽  
Vol 204 (8) ◽  
pp. 1945-1957 ◽  
Author(s):  
Takeshi Egawa ◽  
Robert E. Tillman ◽  
Yoshinori Naoe ◽  
Ichiro Taniuchi ◽  
Dan R. Littman
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Development ◽  
Cell Development ◽  
Cytotoxic T Cell ◽  
Thymocyte Development ◽  
Double Positive ◽  
Interleukin 7 ◽  
Genes Encoding ◽  
Single Positive

Members of the Runx family of transcriptional regulators are required for the appropriate expression of CD4 and CD8 at discrete stages of T cell development. The roles of these factors in other aspects of T cell development are unknown. We used a strategy to conditionally inactivate the genes encoding Runx1 or Runx3 at different stages of thymocyte development, demonstrating that Runx1 regulates the transitions of developing thymocytes from the CD4−CD8− double-negative stage to the CD4+CD8+ double-positive (DP) stage and from the DP stage to the mature single-positive stage. Runx1 and Runx3 deficiencies caused marked reductions in mature thymocytes and T cells of the CD4+ helper and CD8+ cytotoxic T cell lineages, respectively. Runx1-deficient CD4+ T cells had markedly reduced expression of the interleukin 7 receptor and exhibited shorter survival. In addition, inactivation of both Runx1 and Runx3 at the DP stages resulted in a severe block in development of CD8+ mature thymocytes. These results indicate that Runx proteins have important roles at multiple stages of T cell development and in the homeostasis of mature T cells.

scholarly journals Histone Deacetylase 3 Is Required for Efficient T Cell Development

2015 ◽  
Vol 35 (22) ◽  
pp. 3854-3865 ◽  
Author(s):  
Kristy R. Stengel ◽  
Yue Zhao ◽  
Nicholas J. Klus ◽  
Jonathan F. Kaiser ◽  
Laura E. Gordy ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Development ◽  
Hdac Inhibitors ◽  
Cell Receptor ◽  
Cell Development ◽  
Open Chromatin ◽  
Double Negative ◽  
Thymocyte Development ◽  
Double Positive ◽  
Single Positive

Hdac3 is a key target for Hdac inhibitors that are efficacious in cutaneous T cell lymphoma. Moreover, the regulation of chromatin structure is critical as thymocytes transition from an immature cell with open chromatin to a mature T cell with tightly condensed chromatin. To define the phenotypes controlled by Hdac3 during T cell development, we conditionally deletedHdac3using theLck-Cretransgene. This strategy inactivatedHdac3in the double-negative stages of thymocyte development and caused a significant impairment at the CD8 immature single-positive (ISP) stage and the CD4/CD8 double-positive stage, with few mature CD4+or CD8+single-positive cells being produced. WhenHdac3−/−mice were crossed withBcl-xL-,Bcl2-, orTCRβ-expressing transgenic mice, a modest level of complementation was found. However, when the null mice were crossed with mice expressing a fully rearranged T cell receptor αβ transgene, normal levels of CD4 single-positive cells were produced. Thus, Hdac3 is required for the efficient transit from double-negative stage 4 through positive selection.

scholarly journals The effect of in vivo IL-7 deprivation on T cell maturation.

1995 ◽  
Vol 181 (4) ◽  
pp. 1399-1409 ◽  
Author(s):  
S K Bhatia ◽  
L T Tygrett ◽  
K H Grabstein ◽  
T J Waldschmidt
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Present Report ◽  
Critical Role ◽  
Cell Maturation ◽  
Double Negative ◽  
Heat Stable Antigen ◽  
Single Positive

A number of previous studies have suggested a key role for interleukin 7 (IL-7) in the maturation of T lymphocytes. To better assess the function of IL-7 in lymphopoiesis, we have deprived mice of IL-7 in vivo by long-term administration of a neutralizing anti-IL-7 antibody. In a previous report (Grabstein, K. H., T. J. Waldschmidt, F. D. Finkelman, B. W. Hess, A. R. Alpert, N. E. Boiani, A. E. Namen, and P. J. Morrissey. 1993. J. Exp. Med. 178:257-264), we used this system to demonstrate the critical role of IL-7 in B cell maturation. After a brief period of anti-IL-7 treatment, most of the pro-B cells and all of the pre-B and immature B cells were depleted from the bone marrow. In the present report, we have injected anti-IL-7 antibody for periods of up to 12 wk to determine the effect of in vivo IL-7 deprivation on the thymus. The results demonstrate a > 99% reduction in thymic cellularity after extended periods of antibody administration. Examination of thymic CD4- and CD8- defined subsets revealed that, on a proportional basis, the CD4+, CD8+ subset was most depleted, the CD4 and CD8 single positive cells remained essentially unchanged, and the CD4-, CD8- compartment actually increased to approximately 50% of the thymus. Further examination of the double negative thymocytes demonstrated that IL-7 deprivation did, indeed, deplete the CD3-, CD4-, CD8- precursors, with expansion of this subset being interupted at the CD44+, CD25+ stage. The proportional increase in the CD4-, CD8- compartment was found to be due to an accumulation of CD3+, T cell receptor alpha, beta + double negative T cells. Additional analysis revealed that anti-IL-7 treatment suppressed the audition/selection process of T cells, as shown by a significant reduction of single positive cells expressing CD69 and heat stable antigen. Finally, the effects of IL-7 deprivation on the thymus were found to be reversible, with a normal pattern of thymic subsets returning 4 wk after cessation of treatment. The present results thus indicate a central role for IL-7 in the maturation of thymic-derived T cells.

scholarly journals VßGene Family Usage in Spontaneous Lymphomas of AKR Mice: Evidence for Defective Clonal Deletion

1992 ◽  
Vol 2 (2) ◽  
pp. 95-101 ◽  
Author(s):  
Cees de Heer ◽  
Bernard de Geus ◽  
Henk-Jan Schuurma ◽  
Henk Van Loveren ◽  
Jan Rozing
Keyword(s):  
T Cell ◽  
T Cell Development ◽  
Cell Receptor ◽  
Cell Development ◽  
Mesenteric Lymph Nodes ◽  
Double Positive ◽  
Clonal Deletion ◽  
Lymphoma Cells ◽  
Single Positive ◽  
Akr Mice

T-cell receptor (TCR)ß-chain usage and expression of the CD3, CD4, and CD8 differentiation antigens were analyzed in 14 spontaneous AKR lymphomas. Lymphoma cells massively infiltrated and/or proliferated in the organs analyzed (thymus, spleen, and mesenteric lymph nodes), giving rise to a loss of organ structure. One lymphoma occurred only in the thymus, and failed to express CD3, CD4, and CD8. All other lymphomas expressed the CD3/TCR complex. With respect to CD4 and CD8 expression, the lymphomas were either double-negative (DN), double-positive (DP), or single-positive (SP). The frequency of DP (CD4+8+) lymphomas was low compared to the frequency of DP thymocytes in a normal AKR thymus. A substantial heterogeneity was seen in the intensity of CD4 and CD8 expression among various lymphomas, which was independent of the level of CD3 expression. Considering TCR Vßgene family usage, 2 out of 14 lymphomas expressed Vß6. Normally, Vß6+thymocytes are deleted from the thymocyte pool at the immature DP stage of T-cell development in AKR mice. These data support the hypothesis that the lymphocytes in the immature DP stage of T-cell development are susceptible to the induction of AKR lymphomagenesis. The presence of Vß6+lymphoma cells indicates that the lymphomagenesis is accompanied by a defective clonal deletion of cells expressing a possible autoreactive TCR.

scholarly journals Process for immune defect and chromosomal translocation during early thymocyte development lacking ATM

Blood ◽  
2012 ◽  
Vol 120 (4) ◽  
pp. 789-799 ◽  
Author(s):  
Takeshi Isoda ◽  
Masatoshi Takagi ◽  
Jinhua Piao ◽  
Shun Nakagama ◽  
Masaki Sato ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Development ◽  
Chromosomal Translocation ◽  
Cell Development ◽  
Positive Phase ◽  
Deficient Mouse ◽  
Thymocyte Development ◽  
Immune Defect ◽  
Single Positive

Immune defect in ataxia telangiectasia patients has been attributed to either the failure of V(D)J recombination or class-switch recombination, and the chromosomal translocation in their lymphoma often involves the TCR gene. The ATM-deficient mouse exhibits fewer CD4 and CD8 single-positive T cells because of a failure to develop from the CD4+CD8+ double-positive phase to the single-positive phase. Although the occurrence of chromosome 14 translocations involving TCR-δ gene in ATM-deficient lymphomas suggests that these are early events in T-cell development, a thorough analysis focusing on early T-cell development has never been performed. Here we demonstrate that ATM-deficient mouse thymocytes are perturbed in passing through the β- or γδ-selection checkpoint, leading in part to the developmental failure of T cells. Detailed karyotype analysis using the in vitro thymocyte development system revealed that RAG-mediated TCR-α/δ locus breaks occur and are left unrepaired during the troublesome β- or γδ-selection checkpoints. By getting through these selection checkpoints, some of the clones with random or nonrandom chromosomal translocations involving TCR-α/δ locus are selected and accumulate. Thus, our study visualized the first step of multistep evolutions toward lymphomagenesis in ATM-deficient thymocytes associated with T-lymphopenia and immunodeficiency.

scholarly journals Separation of Notch1 Promoted Lineage Commitment and Expansion/Transformation in Developing T Cells

2001 ◽  
Vol 194 (1) ◽  
pp. 99-106 ◽  
Author(s):  
David Allman ◽  
Fredrick G. Karnell ◽  
Jennifer A. Punt ◽  
Sonia Bakkour ◽  
Lanwei Xu ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Development ◽  
Cell Receptor ◽  
Cell Development ◽  
Surface Proteins ◽  
Lineage Commitment ◽  
Double Positive ◽  
Hematopoietic Stem ◽  
Multipotent Progenitor Cells

Notch1 signaling is required for T cell development. We have previously demonstrated that expression of a dominant active Notch1 (ICN1) transgene in hematopoietic stem cells (HSCs) leads to thymic-independent development of CD4+CD8+ double-positive (DP) T cells in the bone marrow (BM). To understand the function of Notch1 in early stages of T cell development, we assessed the ability of ICN1 to induce extrathymic T lineage commitment in BM progenitors from mice that varied in their capacity to form a functional pre-T cell receptor (TCR). Whereas mice repopulated with ICN1 transduced HSCs from either recombinase deficient (Rag-2−/−) or Src homology 2 domain–containing leukocyte protein of 76 kD (SLP-76)−/− mice failed to develop DP BM cells, recipients of ICN1-transduced Rag-2−/− progenitors contained two novel BM cell populations indicative of pre-DP T cell development. These novel BM populations are characterized by their expression of CD3ε and pre-Tα mRNA and the surface proteins CD44 and CD25. In contrast, complementation of Rag-2−/− mice with a TCRβ transgene restored ICN1-induced DP development in the BM within 3 wk after BM transfer (BMT). At later time points, this population selectively and consistently gave rise to T cell leukemia. These findings demonstrate that Notch signaling directs T lineage commitment from multipotent progenitor cells; however, both expansion and leukemic transformation of this population are dependent on T cell–specific signals associated with development of DP thymocytes.

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