用mRNA差异显示方法寻找小鼠胸腺基质细胞差异表达基因

目的 寻找并初步分析小鼠胸腺基质细胞差异表达基因。方法 来源于小鼠胸腺基质细胞系的两株亚克隆细胸4（5）和4（12）,前者可诱导前体T细胞的进一步成熟,分别提以该两株细胞的总RNA,利用mRNA差异显示方法（DD－PCR）筛选4（5）细胞特异表达的基因片段。结果 得到了17个4（5）细胞特异表达的基因片段（expressed sequences tag,EST）,其中14个代表了尚未登录的小鼠新基因,另外3个则分别与小鼠的cytochrome Coxidase,Hsp65,Eps8基因高度同源。结论 DD－PCR方法是一种优良的寻找新基因的方法,小鼠胸腺基质细胞可能分泌或表达更多的新因子或分子。     

T-cell receptor gene rearrangement and its expression in human myeloid leukemia cell lines

ML cell lines (ML-1, -2, and -3) were derived from the cells of a patient with acute myelocytic leukemia preceded by a T-cell malignant lymphoma. A deletion of chromosome 11 (11q-) was common to the affected cells in both neoplastic phases. We report here that the three ML cell lines have DNA rearrangements of the T-cell receptor (TcR)-beta and gamma-chain genes in addition to immunoglobulin heavy-chain gene rearrangement, though they do not have TcR gene messages. The findings presented here indicate that ML cell lines could be used as models for the elucidation of the bilineal nature of hematopoietic neoplastic cells, though they have a biphenotypic (myelomonocytic/T-cell) marker expression.     

T cell receptor diversity in the human thymus

A diverse T cell receptor (TCR) repertoire is essential for adaptive immune responses and is generated by somatic recombination of TCRα and TCRβ gene segments in the thymus. Previous estimates of the total TCR diversity have studied the circulating mature repertoire, identifying 1 to 3 × 10⁶ unique TCRβ and 0.5 × 10⁶ TCRα sequences. Here we provide the first estimate of the total TCR diversity generated in the human thymus, an organ which in principle can be sampled in its entirety. High-throughput sequencing of samples from four pediatric donors detected up to 10.3 × 10⁶ unique TCRβ sequences and 3.7 × 10⁶ TCRα sequences, the highest directly observed diversity so far for either chain. To obtain an estimate of the total diversity we then used three different estimators, preseq and DivE, which measure the saturation of rarefaction curves, and Chao2, which measures the size of the overlap between samples. Our results provide an estimate of a thymic repertoire consisting of 40 to 70 × 10⁶ unique TCRβ sequences and 60 to 100 × 10⁶ TCRα sequences. The thymic repertoire is thus extremely diverse. Moreover, extrapolation of the data and comparison with earlier estimates of peripheral diversity also suggest that the thymic repertoire is transient, with different clones produced at different times.     

T cell receptor expression on immature thymocytes with in vivo and in vitro precursor potential

Immature CD8-CD4- double-negative (DN) thymocytes differentiate intrathymically into CD8+CD4- and CD8-CD4+ thymocytes and migrate to the periphery. This differentiation proceeds through several intermediate phenotypic changes in the expression of CD8 and CD4. We have recently established the existence of a CD8loCD4lo cell population in murine thymus that can repopulate the irradiated thymus in vivo and differentiate rapidly in vitro to CD8+CD4+ double-positive (DP) cells. The CD8loCD4lo cells score as DN upon direct cytofluorometric analysis, yet are distinct from true DN cells by various criteria. Experimental evidence strongly suggests that they are descendants of true DN in the maturation pathway. In the experiments presented here, we further characterize this CD8loCD4lo thymocyte population. Northern blot and RNA protection analysis reveal that these cells transcribe full length mRNA for the T cell receptor (TcR)alpha chain, unlike the less mature interleukin 2 receptor-positive DN thymocytes. Surface expression of the TcR-associated CD3 molecule occurs on approximately 15% of these cells at low levels characteristic of immature cells. In the course of in vitro differentiation a vast majority (approximately 80%) of these cells convert to CD8+CD4+ and significant numbers of the brightly staining DP convertants (11%-34% on day 1 and 48%-68% on day 2) express immature levels of CD3. Our results indicate that CD8lo, CD4lo cells might be the first thymic subset to rearrange TcR alpha chain genes and express TcR alpha/beta heterodimer on the surface at levels characteristic of immature cells. Furthermore, the surface expression of TcR persists on the in vitro progeny of these thymocytes.     

T-cell receptor expression in the T-cell malignancies.

Twenty-eight cases with T-cell neoplasms (10 with T-cell acute lymphoblastic leukemia [T-ALL], 10 with T-lymphoblastic lymphoma, and 8 with peripheral T-cell lymphomas) and 2 cases with reactive lymph nodes were immunohistochemically stained with monoclonal antibodies beta F1, delta TCS1, and WT31; beta F1 antibody recognizes the beta-subunit of T-cell receptor (TCR), whereas delta TCS1 and WT31 recognize the delta- and alpha beta-subunits of TCR, respectively. Five cases with T-ALL, four with T-lymphoblastic lymphoma (T-LL), and seven with peripheral T-cell lymphomas were positive for beta F1. None showed positive reactivity for delta TCS1. One case with T-LL and four cases with peripheral T-cell lymphomas were positive for WT31. Of the nine cases positive for beta F1 among T-ALLs and T-LLs, six were also positive for CD1 (OKT6), whereas six of seven positive cases for CD1 were positive for beta F1. The authors therefore suggest that TCR beta is expressed in the immature T-cells just earlier than or around the same stage of differentiation as those expressing CD1. The authors' immuno-electron microscopy study revealed that positive reactivity for beta F1 was localized predominantly in the cytoplasm of the neoplastic cells in the cases with T-ALL, T-LL and peripheral T-cell lymphomas, and in the cytoplasm of the reactive T-cells. However, it was not localized on the surface membrane. In contrast, positive reactivity for WT31 was localized on the surface membrane of the neoplastic and reactive T-cells. Only half of the cases of peripheral T-cell lymphomas showed positive reactivity for WT31. The authors consider that it may not be a very useful antibody for the detection of TCR alpha beta on the T-cell neoplasms using frozen tissue sections.     

Detection of laminin receptor mRNA in human cancer cell lines and colorectal tissues by in situ hybridization.

The 67-kd high-affinity laminin receptor (67 LR) is a gene product whose expression appears to be associated with the invasive and metastatic phenotype of a variety of human cancer cells. Northern blot hybridization has been routinely used to quantify the level of 67 LR mRNA from total cellular RNA extracts of homogenized tissue specimens or in vitro grown cell populations. This technique is useful to assess the average expression of the 67 LR mRNA of a particular sample but does not provide information about expression in specific cell types nor about heterogeneity of expression from cell to cell. In this study, we analyzed the expression of 67 LR mRNA in four human cancer cell lines with varying degrees of expression of 67 LR protein (renal cancer A-704, breast carcinoma MCF-7/4 and MCF-7/7, and pancreatic cancer Panc-1) using in situ hybridization performed with 67 LR riboprobes. Total cellular RNA was simultaneously extracted from the cell lines and hybridized on Northern blots with a 67 LR cDNA probe to assess the validity of the mRNA detection by in situ hybridization. Sixty-seven LR mRNA expression was higher in Panc-1 and MCF-7/4 cells than in MCF-7/7 and renal carcinoma A-704. There was a direct correlation (R2 = 0.88) between the in situ hybridization analysis and the mRNA levels detected by Northern blot analysis. The in situ hybridization method showed a heterogeneous expression of the 67 LR mRNA in the four cell lines with different subpopulations of cells showing a range from negative to high levels of the message. Sixteen freshly frozen human colorectal tissues (seven adenocarcinomas, five matched normal mucosae, and four adenomas) were also analyzed by in situ hybridization. The 67 LR mRNA was localized in normal and neoplastic epithelial cells. Adenocarcinoma cells showed a 1.6- to 5-fold higher expression (P < 0.02 according to the Wilcoxon-Mann-Whitney test) than did epithelial colonic cells from normal mucosae or adenomas. The signal tended to be stronger in poorly differentiated carcinomas and carcinomas with metastases than in moderately differentiated and nonmetastatic tumors. We conclude that the high expression of 67 LR mRNA in colorectal tumors is due to an increased production by tumor cells. Furthermore, in situ hybridization is an effective method to detect the expression of LR mRNA in cultured cell lines as well as in frozen tissue sections.     

Increased fibronectin mRNA in alveolar macrophages following in vivo hyperoxia.

Oxygen-mediated lung injury can stimulate a fibroproliferative response resulting in the alteration of the pulmonary extracellular matrix and subsequent scarring of parenchymal tissue. Fibronectin (FN), a component of the extracellular matrix, appears in increased quantities in fibrotic lung disease. Alveolar macrophages (AMs) are a potential source of this molecule. Using quantitative in situ hybridization, we demonstrated that AMs from rabbits acutely exposed to 100% oxygen (hyperoxia) for up to 64 h have 20-fold greater levels of FN mRNA relative to cells from control animals. When animals were allowed to recover in room air for up to 72 h after maximal oxygen exposure, AM FN mRNA abundance approached baseline levels. Furthermore, in oxygen-exposed animals, the fraction of lavaged cells expressing FN mRNA was increased 10-fold relative to controls. Although there was marked cell-to-cell variation, we conclude that the AM is a potential source of FN in the events leading to hyperoxia-induced pulmonary fibrosis.     

Development of a genetically-modified novel T-cell receptor for adoptive cell transfer against renal cell carcinoma

A novel α/β T-cell clone with broad reactivity against human clear cell renal cell carcinomas (RCC) was generated from a patient with renal cancer. The T-cell receptor (TCR) from this clone recognizes soluble TNF-related apoptosis inducing ligand bound to death receptor 4, a complex found on the surface of nearly all RCC. In this study, we modified this novel TCR by introducing amino acid (AA) substitutions in its complementarity determining region 2 (CDR2) and CDR3 regions of both chains, to increase its activity. We demonstrated that tumor recognition by PBL, retrovirally-transduced with these TCRs, was decreased or unchanged by substitutions in the TCR beta chain, and in the CDR2α region. Yet some AA substitutions in the CDR3α region at positions 109 and 112 could augment tumor recognition. Specifically, substituting phenylalanine for tyrosine at AA109 (109Y-F) and alanine or lysine for serine at AA112 (112S-K or 112 S-A) augmented tumor recognition. Increased benefit was seen on combining both AA substitutions and a retrovirus encoding the modified TCR 109Y-F/112S-K conferred the best tumor recognition to transduced PBL. This modified TCR retained the recognition pattern of parental clone HC/2G-1 against RCC lines, other tumors and normal tissues. These results document that CDR3α plays an important role in the interaction of the HC/2G-1 TCR and its novel ligand. A phase I/II clinical trial, adoptively transferring autologous PBL transduced with this modified TCR has just begun in patients with metastatic RCC.     

胎儿胸腺发育过程中T细胞抗原受体的表达

目的:检测不同胎龄胎儿胸腺组织内T细胞抗原受体(TCR)的表达及发育规律.方法:18～40周胎儿胸腺组织,采用免疫组织化学SP法检测TCRαβ和TCRγδ的表达. 结果:胚胎21周,胸腺组织开始出现TCRαβ和TCRγδ阳性细胞.TCRαβ阳性细胞主要分布被膜下及小叶间隔中,围绕血管成群分布.TCRγδ阳性细胞的分布与TCRαβ阳性细胞相似, 但细胞数量较TCRαβ阳性细胞少.38周以后胎儿胸腺内TCR阳性细胞主要分布在皮髓质交界处,被膜下及小叶间隔中的TCR阳性细胞较早期少.结论:TCR阳性细胞在胚胎早期开始出现,其分布部位提示局部微环境有利于这些细胞的分化发育.     

Altered interleukin-2 receptor alpha-chain is expressed in human T-cell leukaemia virus type-I-infected T-cell lines and human peripheral blood mononuclear cells of adult T-cell leukaemia patients through an alternative splicing mechanism.

A polymerase chain reaction (PCR) method was used to detect the interleukin-2 receptor alpha-chain (IL-2R alpha) chain which lacks the conventional transmembrane (TM) domain in mRNA from human T-cell leukaemia virus type-I (HTLV-I)-infected cell lines or peripheral blood mononuclear cells (PBMC) isolated from adult T-cell leukaemia (ATL) patients. Primer pairs encompassing the TM domain were selected to generate a 357-base pair (bp) fragment. A 146-bp PCR product was observed consistently in addition to the target 357-bp PCR product in mRNA from HTLV-I-infected cell lines, such as MT-1, MT-2, MT-4 and in PBMC isolated from ATL patients. However, this 146-bp PCR product was undetectable in HTLV-I-negative cell lines. The product was also detected in PBMC from normal individuals if activated in vitro with phytohaemagglutinin but not without stimulation. DNA sequence analyses revealed that exons from 5 to 7, which define a 211-bp region containing the conventional TM domain, were deleted in the 146-bp PCR product. The C-terminal amino acid sequence starting from Gly174 of the 211-bp-deleted molecule was distinct from that of conventional IL-2R alpha as a result of an altered reading frame. We identified a 45000 MW peptide generated from IL-2R alpha mRNA through this exon skip in cell lysate of MT-1 and MT-2 by Western blot analyses using an antibody raised against the peptides specific to an altered IL-2R alpha. Our results indicate that an altered IL-2R alpha chain is expressed in HTLV-I-infected T lymphocytic cell lines and in ATL patients.     

Adoptive transfer of murine host protection to salmonellosis with T-cell growth factor-dependent, Salmonella-specific T-cell lines.

A spent medium antigen was prepared from the avirulent RIA strain of Salmonella typhimurium. Lymph node cells isolated from female BALB/c mice injected subcutaneously with the spent medium antigen exhibited antigen-specific proliferation. By using these cells and T-cell growth factor, continuous spent medium antigen-specific, Thy 1.2-sensitive lines were generated. These cells exhibited antigen-specific proliferation in vitro and were effective in inducing significant (P less than 0.01) host protection when adoptively transferred to naive syngeneic mice.     

Granulocyte-macrophage colony-stimulating factor elevates invariant chain expression in immature myelomonocytic cell lines.

Invariant chain (Ii) plays an important role in major histocompatibility complex (MHC) class II antigen processing and presentation and is constitutively synthesized in B lymphocytes, in macrophages, dendritic cells and in some epithelial cells. It has been shown that interferon-gamma, tumour necrosis factor-alpha and interleukin-4 co-regulate Ii and MHC class II expression in various cell types. We describe here a novel regulation of Ii expression in macrophages. Treatment of the premature monocytic cell lines WEHI 265.1, M1 and WEHI-3B with recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) strongly enhances Ii expression while class II expression is not induced. In contrast, GM-CSF did not enhance Ii in mature macrophage cell lines. The increase of Ii expression in WEHI 265.1 cells takes several days. This long induction time, and a difference in activity between GM-CSF-conditioned medium and GM-CSF, together suggest that GM-CSF stimulates WEHI 265.1 cells to secrete a factor that modulates Ii expression. These results may imply a class II-independent function of Ii, which we discuss in this paper.