Progressive changes in T₁, T₂ and left-ventricular histo-architecture in the fixed and embedded rat heart

Chemical tissue fixation, followed by embedding in either agarose or Fomblin, is common practice in time-intensive MRI studies of ex vivo biological samples, and is required to prevent tissue autolysis and sample motion. However, the combined effect of fixation and sample embedding may alter tissue structure and MRI properties. We investigated the progressive changes in T(1) and T(2) relaxation times, and the arrangement of locally prevailing cardiomyocyte orientation determined using diffusion tensor imaging, in embedded ex vivo rat hearts fixed using Karnovsky's solution (glutaraldehyde-formaldehyde mix). Three embedding media were investigated: (i) standard agarose (n = 3 hearts); (ii) Fomblin (n = 4 hearts); and (iii) iso-osmotic agarose (n = 3 hearts); in the latter, the osmolarity of the fixative and embedding medium was adjusted to 300 mOsm to match more closely that of native tissue. The T(1) relaxation time in the myocardium showed a pronounced decrease over a 48-h period following embedding in Fomblin (-11.3 ± 6.2%; mean ± standard deviation), but was stable in standard agarose- and iso-osmotic agarose-embedded hearts. The mean myocardial T(2) relaxation time increased in all embedded hearts: by 35.1 ± 14.7% with standard agarose embedding, 13.1 ± 5.6% with Fomblin and 13.3 ± 1.4% with iso-osmotic agarose. Deviation in the orientation of the primary eigenvector of the diffusion tensor occurred in all hearts (mean angular changes of 6.6°, 3.2° and 1.9° per voxel after 48 h in agarose-, Fomblin- and iso-osmotic agarose-embedded hearts, respectively), indicative of progressive structural changes in myocardial histo-architecture, in spite of previous exposure to fast-acting tissue fixation. Our results suggest that progressive structural changes occur in chemically fixed myocardium, and that the extent of these changes is modulated by the embedding medium, and by osmotic gradients between the fixative in the tissue and the surrounding medium.     

Harnessing γδ T cells in anticancer immunotherapy

γδ T lymphocytes are involved in the stress response to injured epithelia and in tissue homeostasis by limiting the dissemination of malignant or infected cells and by regulating the nature of the subsequent adaptive immune response. γδ T cells have potent MHC-unrestricted cytotoxicity, a high potential for cytokine release and broad-spectrum recognition of cancer cells, and as such, are attractive effectors for cancer immunotherapy. Current expectations are going beyond ex vivo manipulation of the Vγ9Vδ2 T subset, and target novel γδ T cell subsets, properties or receptors, to harness these unconventional T lymphocytes against cancer. This Opinion article discusses novel aspects of γδ T cell function during the course of anticancer therapies, as well as new avenues for their clinical implementation.     

γ/δT细胞简介

γ/δT细胞是近 10多年来人们新认识到的一种T细胞亚群 ,该细胞有许多独特特征 ,在抗感染、抗过敏、肿瘤监测及自身免疫病中起着一定作用。本文对该细胞亚群的受体基因、抗原特异性、分布、作用等进行了综述。     

TNFα −857 C/T and TNFR2 +587 T/G polymorphisms are associated with cystic fibrosis in Iranian patients

Identification of modifier genes influencing phenotype of cystic fibrosis (CF) patients has become a challenge in CF pathophysiology, prognostic estimations and development of new therapeutic strategies. The aim of this study was to explore the association between four genetic polymorphisms of three modifier genes with CF, by comparing their alleles, genotypes and haplotype frequencies in patients and controls. In this favor, two regulatory polymorphic loci in TNFα promoter (−857C/T, rs1799724 and -238A/G, rs361525) and two functional polymorphic loci in TNFR1 (+36A/G, rs767455) and TNFR2 (+587T/G, rs1061622) were genotyped in 70 patients and 79 controls, using PCR-RFLP. Clinical pulmonary data were also recorded from all studied patients. Results indicated that an association was observed between both T allele and CT/TT genotypes of TNFα (P = 0.0005, OR = 7.06, 95% CI = 3.71–13.45) with CF under dominant model of inheritance. GG genotype of TNFR2 +587 (P = 0.0005, OR = 4.92, 95%CI = 2.34–10.34) was significantly associated with CF using recessive model. Consistently, more severe pulmonary disorder was found for patients carrying either T dominant allele of TNFα −857 or GG genotype of TNFR2 +587 polymorphic sites. Despite an association of A-T and G-T haplotypes with CF, no significant association was found between these haplotypes and clinical parameters of CF. Overall, TNFα −857 T allele and GG genotype of TNFR2 +587 were more frequent in CF patients compared to healthy controls and hence, they showed an association with CF and severe pulmonary phenotype in Iranian patients.     

Accumulation of γ/δ T Cells in Human Dysgerminoma and Seminoma: Roles in Autologous Tumor Killing and Granuloma Formation

The precise biological function of a subset of T cells bearing γ/δ T cell receptor (TCR) remains poorly understood. The present study demonstrated the presence of γ/δ T cells in tumor-infiltrating lymphocytes (TIL) and peripheral blood lymphocytes (PBL) of human patients with dysgerminoma and seminoma when determined by flow cytometry and in situ immunohistochemical staining. TIL contained a high percentage of γ/δ T cells, ranging from 17.3 to 35.1%. γ/δ T cells often accumulated within the granulomatous inflammation of tumor tissues. The majority of γ/δ T cells were Vγ9/Vδ2+ cells. Freshly isolated PBL, TIL and purified γ/δ T cells showed autologous tumor killing (ATK) activity, which could be inhibited by monoclonal antibodies (mAb) against Vδ2. Furthermore, two γ/δ T cell clones established from TIL showed cytotoxicity against autologous and allogeneic dysgerminoma, while they had low or no lytic effects on other cell types including carcinomas of ovary and tumor cell lines such as K562, Daudi and Molt-4. Lysis of autologous tumor cells by the clone was inhibited completely by anti-Vδ2 mAb and partially by mAb against CD3, LFA-1α and ICAM-1 molecules, while it was resistant to anti-CD8, anti-HLA-ABC and anti-HLA-DR mAb. Supernatants produced by γ/δ T cell clones induced adhesion, aggregation and increased DNA synthesis of monocytes and some characteristics of activated macrophages or epithelioid cells. Tumor necrosis factor (TNF)-α, granulocyte-macrophage colony stimulating factor (GM-CSF) and interferon (IFN)-γ were detected in the supernatants of γ/δ T cell clone. These results suggest that γ/δ T cells accumulating in dysgerminoma and seminoma exhibit ATK activity through Vγ9/δ2 TCR and these γ/δ T cells also play a role in the formation of granulomatous inflammation, which is associated with human dysgerminoma and seminoma.     

Alterations in the expression of signal-transducing CD3ζ chain in T cells from patients with chronic inflammatory/autoimmune diseases

The CD3ζ chain, a component of the T cell receptor (TCR)/CD3 complex, is considered to be a limiting factor in the assembly and transport of the TCR/CD3 complex to the cell surface and is crucial to receptor signaling function. Recent studies have demonstrated altered expression and function of this signal transduction molecule in T and natural killer cells in patients with chronic inflammatory/autoimmune diseases. In this review, current knowledge concerning the expression of CD3ζ chain as well as the mechanisms responsible for abnormal expression of this molecule in systemic lupus erythematosus, rheumatoid arthritis, and childhood idiopathic nephrotic syndrome are summarized.     

Autoreactive T cells in endocrine/organ-specific autoimmunity: why has progress been so slow?

It has been generally accepted that T cells play a critical role in endocrine autoimmune diseases. Immunotherapy aimed at T cells usually intervenes in the disease process. Yet, it has proven very difficult to identify the pathogenic T cells. This is partly caused by lack of measures to detect autoreactive T cells in a specific, sensitive and reproducible fashion as is achievable for determination of autoantibodies. There are, however, more explanations for the perhaps disappointing progress in this area: unlike autoantibodies, the relevant (disease-associated) autoreactive T cells act in the tissue lesion, and only circulate in very low precursor frequencies. Moreover, T cell autoreactivity is counteracted by various mechanisms of immune regulation. Candidate target autoantigens of T cells have been identified by autoantibodies, while there is little evidence that these autoantibodies are pathogenic. It is therefore conceivable that additional T cell targets exist. Finally, results from experimental animal models of endocrine autoimmunity have raised false expectations. Nonetheless, significant progress in our understanding of the contribution of (autoreactive) T cells to organ-specific destruction and autoimmune disease has been achieved. Although cross-sectional detection of autoreactive T cells bears little relevance to diagnosis, longitudinal studies have proven useful in determining the fate of islet implantation in type 1 diabetes patients, defined the immunological efficacy of immuno-intervention studies, and have led to definition of relevant target autoantigens and peptides that will help to monitor disease-associated autoimmunity. In conclusion, progress in the area of autoreactive T cells in the pathogenesis of type 1 diabetes may have seemed slow in the eyes of the beholder, but in fact, studies on T cells have contributed significantly to the unravelling of the pathogenic processes leading to the definition of appropriate targets for immuno-intervention.     

Respiratory infection promotes T cell infiltration and amyloid-β deposition in APP/PS1 mice

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by deposits of amyloid-β and neurofibrillary tangles. It has been suggested that inflammatory changes are associated with disease; however, it has not been established whether these are a consequence of ongoing neurodegeneration or whether inflammation itself contributes to disease pathogenesis. Recent studies suggest that exposure to infection can accelerate cognitive decline in AD patients, and pathogens have been detected in the AD brain. However, the influence of infection on neuroinflammation and pathology remains poorly understood. In this study, we examined the effect of a peripheral infection on AD pathology in APP/PS1 mice. We found that, 8 weeks after infection with the Gram negative respiratory pathogen Bordetella pertussis, there was significant infiltration of IFNγ- and IL-17–producing T cells and NKT cells in older APP/PS1 mice. This was accompanied by increased glial activation and amyloid-β deposition. The data suggest that infection is a critical factor in the progression of AD, emphasising the importance of early diagnosis and treatment of infections in elderly individuals.     

Selective Function of PKC-θ in T cells

T cell activation is a critical process in initiating adaptive immune response since only through this process the naive antigen specific T cells differentiate into armed effector T cells that mediate the actual immune response. During T cell activation, naive T cells undergo clonal expansion and acquire the capability to kill target cells infected with pathogens or produce cytokines essential for regulating immune response. Inappropriate activation or inactivation of T cells leads to autoimmunity or severe immunodeficiencies. PKC-θ is selectively expressed in T cells and required for mediating T cell activation process. Mice deficient in PKC-θ exhibit defects in T cell activation, survival and activation-induced cell death. PKC-θ selectively translocates to immunological synapse and mediates the signals required for activation of NF-κB, AP1 and NFAT that are essential for T cell activation. Furthermore, PKC-θ^-│- mice displayed multiple defects in the development of T cell-mediated immune responses in vivo. PKC-θ is thus a critical molecule that regulates T cell function at multiple stages in T cell-mediated immune responses in vivo.     

Anti-ergotypic T cells in naïve rats

T regulatory cells play an important role in regulating T cell responses. Anti-ergotypic T cells are a subset of regulatory T cells that proliferate in response to activation markers, ergotopes, expressed on activated, and not on resting syngeneic T cells. Here we report the presence of anti-ergotypic T cells in lymph nodes, spleens and thymuses of naive rats. The development of anti-ergotypic T cells appeared to be independent of antigen priming, as thymocytes from one-day old rats exhibited significant anti-ergotypic proliferative responses. The anti-ergotypic T cells were found to be of the CD8+ phenotype, and included both TCRalpha/beta+ and TCRgamma/delta+ T cells. The TCRgamma/delta+ anti-ergotypic T cells secreted IFNgamma and TNFalpha in response to activated T cells; the TCRalpha/beta+ T cells proliferated but did not secret detectable cytokines. We found that the interaction between the anti-ergotypic T cells and stimulator T cells required cell-to-cell contact between the T cells. Professional APCs were not needed. The response of the TCRalpha/beta+CD8+ anti-ergotypic T cells was MHC-I restricted and B7-CD28 dependent; the response of the TCRgamma/delta+ anti-ergotypic T cells was B7-CD28 dependent, but was not inhibited by antibodies to classical MHC-I or MHC-II molecules. The existence of anti-ergotypic T cells in naive animals suggests that these cells might have a role in the regulation and maintenance of the immune system.     

015 γ/δT细胞简介

γ/δT细胞是近10多年来人们新认识到的一种T细胞亚群,该细胞有许多独特特征在抗感染、抗过敏、肿瘤监测及自身免疫病中起着一定作用.本文对该细胞亚群的受体基因、抗原特异性、分布、作用等进行了综述.     

血小板/T细胞活化抗原1

１９８５年Ｂｕｒｎｓ等以活化Ｔ细胞为免疫原制备了抗活化Ｔ细胞表面抗原的单克隆抗体,并将其中１株单克隆抗体Ｌｅｏ－Ａ１识别的抗原命名为人Ｔ细胞系特异性活化抗原１（Ｔｌｉｎｅａｇｅ－ｓｐｅｃｉｆｉｃａｃｔｉｖａｔｉｏｎａｎｔｉｇｅｎ１,ＴＬｉＳＡ１）,实...     

皮肤T/NK细胞EB病毒感染淋巴组织增殖性疾病及NK/T细胞淋巴瘤

EB病毒(Epstein-Barr virus,EBV)在全世界人群中普遍易感,可以感染B、T及NK细胞。皮肤T/NK细胞感染EBV与多种疾病的发生有关,其病理特征对疾病的诊断及预后有重要意义。现对皮肤NK/T细胞淋巴瘤及EBV阳性T/NK淋巴组织增殖性疾病的临床病理特点进行综述。