CD4+CD25+ regulatory T cells: I. Phenotype and physiology

The immune system protects us against foreign pathogens. However, if fine discrimination between self and non-self is not carried out properly, immunological attacks against self may be launched leading to autoimmune diseases, estimated to afflict up to 5% of the population. During the last decade it has become increasingly clear that regulatory CD4⁺CD25⁺ T cells (T_reg cells) play an important role in the maintenance of immunological self-tolerance, and that this cell subset exerts its function by suppressing the proliferation or function of autoreactive T cells. Based on human and murine observations, this review presents a characterization of the phenotype and functions of the Treg cells in vitro and in vivo . An overview of the surface molecules associated with and the cytokines produced by the Treg cells is given and the origin, activation requirements and mode of action of the Treg cells are discussed. Finally, we address the possibility that Treg cells may play a central role in immune homeostasis, regulating not only autoimmune responses, but also immune responses toward foreign antigens.     

The hevein domain of the major latex-glove allergen Hev b 6.01 contains dominant T cell reactive sites

BACKGROUND: Sensitization to natural rubber latex (Hevea brasiliensis) is a major cause of occupational asthma and rhinitis affecting frequent latex-glove users. Hev b 6.01, a known major latex allergen, is cleaved naturally into hevein (4.7 kDa) and a C-terminal fragment (14 kDa). Hevein is an abundant protein in latex-glove extracts. As the immune response to allergens is initiated by activation of allergen-specific CD4(+) T cells, identification of dominant T cell epitopes is crucial for the development of specific immunotherapy. OBJECTIVE: To identify dominant T cell epitopes of Hev b 6.01 in latex-allergic glove users. METHODS: Ten latex-allergic frequent glove users and six non-latex-allergic atopic control subjects were selected, based on clinical symptoms and positive latex-specific serum IgE. Serum IgE reactivity to glove extract and recombinant Hev b 6.01 (rHev b 6.01) were analysed by ELISA. Latex-specific short-term oligoclonal T cell lines were generated from peripheral blood of latex-allergic subjects. These lines were tested for proliferative responses to overlapping 20-mer peptides of the Hev b 6.01 molecule. CD4(+) T cell intracellular cytokines, IL-4 and IFN-gamma were assessed following stimulation with immobilized anti-CD3 in the presence of IL-2. RESULTS: All ten of the latex-allergic patients showed serum IgE binding to glove extract while eight of these also showed IgE binding to rHev b 6.01 by ELISA. Western blotting confirmed reactivity with rHev b 6.01 at around 20 kDa. T cell proliferation assays showed that latex-specific T cell lines from all subjects responded to one or more peptides, with greatest frequency of reactivity to peptides Hev b 6.01 p(10-29) and Hev b 6.01 p(19-38) in the hevein domain. An allergic-type cytokine profile with considerable IL-4 in addition to IFN-gamma was evident from intracellular cytokine staining. CONCLUSION: Hevein is an important T cell as well as B cell immunogen and contains dominant T cell reactive sites.     

Infection dynamics and virus-induced apoptosis in cell culture-based influenza vaccine production—Flow cytometry and mathematical modeling

Cell culture-based influenza vaccine manufacturing is of growing importance. Depending on virus strains, differences in infection dynamics, virus-induced apoptosis, cell lysis and virus yields are observed. Comparatively little is known concerning details of virus–host cell interaction on a cellular level and virus spreading in a population of cells in bioreactors. In this study, the infection of MDCK cells with different influenza A virus strains in lab-scale microcarrier culture was investigated by flow cytometry. Together with the infection status of cells, virus-induced apoptosis was monitored. A mathematical model has been formulated to describe changes in the concentration of uninfected and infected adherent cells, dynamics of virus particle release (infectious virions, hemagglutinin content), and the time course of the percentage composition of the cell population.     

The Effect of Desensitization Protocols on Human Splenic B-Cell Populations In Vivo

Rituximab, intravenous immunoglobulin (IVIG) and rabbit antithymocyte globulin (rATG) all have been suggested to have an effect on antibody producing cells, however, supporting data are lacking. To assess the impact of these agents on splenic B‐cell populations in vivo, we retrospectively examined 25 spleens removed from patients treated with these agents as part of desensitization protocols in either ABO incompatible or positive crossmatch living donor kidney transplantation. These were compared to control (CTL) spleens removed for trauma. CTLs and spleens removed at transplant after multiple pretransplant plasmaphereses (PP) plus low‐dose IVIG showed similar large numbers of naïve B cells (CD20⁺ and CD79⁺), plasma cells (CD138⁺) and memory B cells (CD27⁺ cells). Adding rituximab to this PP/IVIG regimen reduced the number naïve B cells, but had no effect on memory or plasma cells. Combination treatment (PP/IVIG, rituximab and rATG) showed a trend toward the reduction of CD27⁺ cells, but again plasma cells were unchanged. We conclude that none of these protocols reduces splenic plasma cells in vivo. PP/low‐dose IVIG does not alter splenic B cells, but the addition of rituximab decreases mature B cells. Memory B cells may be affected by combination therapy including rATG and requires further study.     

NK Cells Rapidly Reject Allogeneic Bone Marrow in the Spleen Through a Perforin- and Ly49D-Dependent, but NKG2D-Independent Mechanism

We have used a sensitive and specific in vivo killing assay to monitor the kinetics, anatomic location and mechanisms controlling NK-mediated rejection of Balb/c bone marrow by C57BL/6 natural killer (NK) cells. We find that NK killing of fully allogeneic bone marrow is a rapid, highly efficient process, leading to substantial rejection of transplanted marrow within 6 h of transplant and elimination of 85% of the transplanted cells within 2 days. NK-mediated rejection occurred predominantly in the spleen, with sparing of rejection in the bone marrow and lymph nodes. Rejection was dependent on Perforin gene function, but was independent of interferon-gamma. Finally, rejection of Balb/c bone marrow by B6 NK cells required signaling through the Ly49D receptor, but occurred despite blockade of NKG2D, which distinguishes these results from previous studies using semiallogeneic transplant pairs. These results identify NK cells as highly active mediators of bone marrow rejection, and suggest that inhibiting NK function early during transplantation may increase the efficiency of engraftment and allow successful engraftment of limiting doses of donor bone marrow.     

Nurr1基因转染人脐血间充质干细胞诱导分化为多巴胺能神经元的实验研究

目的探讨外源性Nurrl基因修饰的人脐血间充质干细胞在基因重组成纤维细胞生长因子-8(FGF8)和音猬因子(Shh)诱导下体外分化为多巴胺能神经元的情况。方法间充质干细胞被随机分为A组(对照组)、B组(Nurrl组)、C组(FGF8+Shh组)及D组(Nurrl+FGF8+Shh),采用脂质体法将pcDNA3.1-Ntrr1转染B、D组间充质干细胞,Western blot观察Nurr1基因表达情况,并在神经元条件培养液中进行增殖培养和诱导分化,间接免疫荧光染色法鉴定细胞性质,高效液相色谱法测定多巴胺含量。结果Western blot结果显示转染后Nurr1蛋白表达明显增高。A组和B组未发现酪氨酸羟化酶(TH)阳性细胞,而C组和D组TH阳性细胞分别为10．12％±2．65％及25．36％±3．13％,多巴胺含量分别为(43．6±2．1)nmol／L及(83．2±3．5)nmol／L,差异均有显著性意义(P< 0．01)。结论人脐血间充质干细胞在FGF8和Shh诱导下可以分化为多巴胺能神经元,外源性Nurr1基因修饰后,分化为多巴胺能神经元的数量增加。     

慢性乙型病毒性肝炎治疗新方法

就当前慢性乙肝治疗的新方法、新进展作一综述。     

Age, lens transmittance, and the possible effects of light on melatonin suppression

Recently it has been suggested that a previously undetected, rhodopsin-based, visual pigment, located in some retinal ganglion cells and having a peak sensitivity around 460 nm, may be responsible for light-induced melatonin suppression and, perhaps, maintenance of the circadian rhythm. Using data from the literature, it is shown that, as absorption in the crystalline lens for shorter visible wavelengths increases substantially with age, while the pupil diameter tends to decrease, the effective retinal exposure received under the same ambient lighting conditions by the pigment is almost 10 times lower in an old, as compared with a young, eye. Interestingly, replacement of the old crystalline lens by an intraocular implant restores the exposure to youthful levels. The possible effects of these changes with age on circadian rhythms are discussed.     

Serial in vivo MR tracking of magnetically labeled neural spheres transplanted in chronic EAE mice.

Neural stem cell (NSC) transplantation has been shown to attenuate the severity of experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). Central to the future success of NSC transplantation in MS is the ability of transplanted cells to migrate from the site of transplantation to relevant foci of disease. Using magnetically labeled mouse neurospheres and human embryonic stem cell (hESC)-derived neurospheres, we applied serial magnetic resonance imaging (MRI) to assess the biodynamics of transplanted cell migration in a chronic mouse EAE model. Magnetic labeling did not affect the in vitro and in vivo characteristics of cells as multipotential precursors. Cell migration occurred along white matter (WM) tracts (especially the corpus callosum (CC), fimbria, and internal capsule), predominantly early in the acute phase of disease, and in an asymmetric manner. The distance of cell migration correlated well with clinical severity of disease and the number of microglia in the WM tracts, supporting the notion that inflammatory signals promote transplanted cell migration. This study shows for the first time that hESC-derived neural precursors also respond to tissue signals in an MS model, similarly to rodent cells. The results are directly relevant for designing and optimizing cell therapies for MS, and achieving a better understanding of in vivo cell dynamics and cell-tissue interactions.