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At least 55 records · Page 3Linked to original sources
PubMed2000

Prolongation of allograft survival by Nippostrongylus brasiliensis is associated with decreased allospecific cytotoxic T lymphocyte activity and development of T cytotoxic cell type 2 cells.

BACKGROUND: We have demonstrated that infection with Nippostrongylus brasiliensis (Nb), which induces strong type 2 responses, prolongs kidney allograft survival in rats. Here, we confirm that this effect is not species-specific and address immune modulation in allospecific T-cell responses mediated by nematode infection. METHODS: C57BL/6 mice were injected with Nb or phosphate-buffered saline. Four days later, mice were transplanted with BALB/c hearts and graft survival was assessed. In other experiments, Nb-infected mice were immunized with BALB/c spleen cells and allospecific T-cell responses were determined in vitro. RESULTS: In this study, we show that Nb prolongs cardiac allograft survival in mice. Further, spleen T cells from Nb-infected, allo-immunized mice exhibit reduced allospecific cytotoxic T-lymphocyte activity. In contrast, allospecific proliferation of T cells in the mixed lymphocyte reaction was not reduced by Nb, ruling out immunosuppression as the mechanism of Nb-induced allograft survival. Nb infection induced IL-4 and IL-6 and inhibited IFN-gamma production by T cells in response to allo-antigen. Furthermore, anti-IL-4 treatment reduced allospecific T-cell proliferation from Nb-infected but not control mice, indicating that type 2 allospecific T cells develop in the presence of Nb. We also double-stained T cells for CD8 and IL-4 and showed that Nb induces an 8-fold increase in Tc2 cell numbers. CONCLUSIONS: These results are consistent with a hypothesis that Nb mediates prolongation of allograft survival through induction of type 2 immunity, including the development of regulatory Tc2 cells, and subsequent inhibition of allospecific cytotoxic T-lymphocyte activity.

Animals↗
PubMed2002

Characterization of prostate cell types by CD cell surface molecules.

A set of monoclonal antibodies raised against lymphocyte cell surface molecules, the cluster designation (CD) antigens, was used to distinguish the constituent cell types of the prostate. The luminal secretory epithelial, basal epithelial, fibromuscular stromal, nerve sheath, and endothelial cells express distinctive complements of cell surface molecules that were identified by immunohistochemistry using 152 commercially available antibodies. Many of the CD antibodies stained lymphocyte populations in the prostate. These lymphocyte populations were grouped into abundance classes of rare, moderate, and high. Some of these molecules are expressed by multiple cell types, both parenchymal and lymphoid; others are expressed by only one cell type. Distinctive patterns of CD expression, which are most similar to the expression pattern of prostate luminal cells, also characterize a small series of Gleason score 6 prostate cancers. The cell-type specificity of CD molecules increases the prospect of isolating specific cell populations, using such techniques as laser capture microdissection and flow cytometry, for cell-specific molecular studies.

Adenocarcinoma↗
PubMed2003

Susceptibility of immature and mature Langerhans cell-type dendritic cells to infection and immunomodulation by human cytomegalovirus.

Human cytomegalovirus (CMV) infection initiates in mucosal epithelia and disseminates via leukocytes throughout the body. Langerhans cells (LCs), the immature dendritic cells (DCs) that reside in epithelial tissues, are among the first cells to encounter virus and may play important roles in the immune response, as well as in pathogenesis as hosts for viral replication and as vehicles for dissemination. Here, we demonstrate that CD34(+) progenitor cell-derived LC-type DCs exhibit a differentiation state-dependent susceptibility to CMV infection. In contrast to the small percentage (3 to 4%) of the immature LCs that supported infection, a high percentage (48 to 74%) of mature, LC-derived DCs were susceptible to infection with endotheliotropic strains (TB40/E or VHL/E) of CMV. These cells were much less susceptible to viral strains AD169varATCC, TownevarRIT(3), and Toledo. When exposed to endotheliotropic strains, viral gene expression (IE1/IE2 and other viral gene products) and viral replication proceeded efficiently in LC-derived mature DCs (mDCs). Productive infection was associated with downmodulation of cell surface CD83, CD1a, CD80, CD86, ICAM-1, major histocompatibility complex (MHC) class I, and MHC class II on these cells. In addition, the T-cell proliferative response to allogeneic LC-derived mDCs was attenuated when CMV-infected cultures were used as stimulators. This investigation revealed important characteristics of the interaction between CMV and the LC lineage of DCs, suggesting that LC-derived mDCs are important to viral pathogenesis and immunity through their increased susceptibility to virus replication and virus-mediated immune escape.

Antigens, CD34↗
PubMed1989

Cell type expression mediated by cell cycle events, and signaled by mitogens and growth inhibitors.

It is initially pointed out that the majority of factors that induce cell type expression in mature precursor cells are either mitogens or growth inhibitors. On the basis of available data, a theoretical model of regulation of cell type expression for each group of factors is proposed. In model A the mitogen affects the expression of cell type through the positive control of cell cycle progression, while in model B the growth inhibitor induces the negative control of cell cycle progression, which in its turn causes the cell type expression. In connection with those two models, various systems of cell type expression are classified into three groups. In model A systems, the cell lineage has an option of autotypic and allotypic cell types. The former is expressed in the absence of added mitogen, and the latter is expressed in its presence. In model B systems the cell lineage-specific cell type is expressed by the negative cell cycle control induced by the growth inhibitor. In model A-B systems both mitogen and inhibitor are needed in tandem for the expression of a cell type. The second major point made is that the expression of cell type follows the negative control of cell cycle progression even in model A systems. However, in this system the control occurs spontaneously. This suggests that the negative control is essential for cell type expression in all systems, and directly precedes the expression. In contrast, the positive control induced by exogenous mitogen is not required in the expression in model B systems or in that of autotypic cell types in model A systems. The third point is that on the basis of the hypothesis of replication-transcription coupling, proposed by Sauer and colleagues, it is speculated that the pattern of early-replicating genes may be functioning as the potential gene transcription pattern for cell type expression in precursor cells. If this pattern is perpetuated through cell generations, the original cell type specificity of the precursor cell lineage should be maintained. If this pattern is modified by the positive control of cell cycle progression in model A systems, the potential transcriptional pattern for the allotypic pathway may emerge. Furthermore, it is proposed that the realization of the potential pattern may depend on a signal, informing the completion of the negative control of cell cycle progression. Thus in all cell lineages, when the negative cell cycle control is completed, chromatin receives this signal, and the potential transcription pattern is converted into cell type differentiation.(ABSTRACT TRUNCATED AT 400 WORDS)

Cell Cycle↗
PubMedDate not supplied

[Markers of retinal-type cell differentiation in studies of eye development and regeneration in vertebrates].

Data on the use of various immunochemical markers specifically indicating cell types of the neural retina and pigment epithelium are reviewed. It is demonstrated how this approach can be applied to the analysis of specific features of vertebrate retinal development, including the order and timing of differentiation of the main cell types, their interdependence in the course of this process, and factors controlling the latter. Problems concerning the state of differentiation and its change in the cells of retinal pigment epithelium and glial cells are discussed in respect to their analysis with the aid of specific protein markers. The current state of retina regeneration research involving the use of labelled cell sources and regenerated cells in lower vertebrates is analyzed. Problems in the search for new markers of retinal photoreceptor, macroglial, and microglial cells and their use in experiments are addressed.

Animals↗
PubMed1986

Ultrastructure of mouse vallate taste buds: II. Cell types and cell lineage.

The lifespan of cells in the mouse taste bud was examined with high-voltage electron microscopic (HVEM) autoradiography (ARG) after giving a single injection of 3H-thymidine. Animals were killed at 1 hour, 6 hours, 12 hours, 24 hours, and then daily up through 10 days postinjection. Lingual tissues were prepared for HVEM ARG so that we could identify and characterize labeled cells. Four categories of taste cells were identified: basal, dark, intermediate, and light cells. Basal cells were polygonal cells located near the basolateral sides of the taste buds and were characterized primarily by the presence of filaments attached to the nuclear envelope. Dark and light cells had the typical features described by previous authors. Intermediate cells had features in between those of dark and light cells. Over 90% of the cells labeled in the first 2 days following injection of 3H-thymidine were basal cells. Labeled dark cells appeared 6 hours after injection, reached their peak incidence at the fourth day postinjection, and then gradually decreased. Labeled intermediate cells were identified after the appearance of dark cells (12 hours) and reached a peak incidence at the fifth day after injection of 3H-thymidine. Lastly, labeled light cells were first observed on the fourth day postinjection and continued to increase until the tenth day, when they constituted 45% of the labeled cells. These data support the hypothesis that there is one cell line in the mouse vallate taste bud that undergoes morphological changes in its lifespan.

Animals↗
PubMedDate not supplied

Evidence for heterogeneity in a small squamous cell type ('light' cells) in the rabbit corneal epithelium--a scanning electron microscope study. Corneal epithelial squamous cells.

The rabbit corneal epithelial surface, as viewed by scanning electron microscopy (SEM), is composed of a mosaic of polygonal cells with different appearances (light, medium and dark) with the lighter cells having a characteristically high density of microplicae. From the central zone of the corneal epithelial surface of 16 female New Zealand White rabbits (2 kg), the lighter-appearing cells had an average area of 108 +/- 47 microns2 (n = 567, +/-SD). A subgroup of atypical lighter cells had an average area of 294 +/- 67 microns2 (n = 53) compared to typical light cells of 88 +/- 12 microns (n = 514). These atypical lighter cells had fused microplicae at their periphery (instead of a uniform arrangement of densely packed microplicae), tended to be rounder in shape (as opposed to being angular), could show signs of desquamation and were not decorated with the epithelial craters found on almost all (92%) other light cells. All of these features are suggestive of these atypical lighter cells being the terminal phenotype of the light cells just prior to desquamation from the ocular surface. The observation of the desquamation of lighter cells supports a hypothesis that they constitute a distinct sub-population of cells at the corneal epithelial surface.

Animals↗
PubMed2003

Enrichment of microbial community generating electricity using a fuel-cell-type electrochemical cell.

A fuel cell was used to enrich a microbial consortium generating electricity, using organic wastewater as the fuel. Within 30 days of enrichment the maximum current of 0.2 mA was generated with a resistance of 1 kOhms. Current generation was coupled to a fall in chemical oxygen demand from over 1,700 mg l(-1) down to 50 mg l(-1). Denaturing gradient gel electrophoresis showed a different microbial population in the enriched electrode from that in the sludge used as the inoculum. Electron microscopic observation showed a biofilm on the electrode surface and microbial clumps. Nanobacteria-like particles were present on the biofilm surface. Metabolic inhibitors and electron acceptors inhibited the current generation. 16S ribosomal RNA gene analysis showed a diverse bacterial population in the enrichment culture. These findings demonstrate that an electricity-generating microbial consortium can be enriched using a fuel cell and that the electrochemical activity is a form of anaerobic electron transfer.

Bacteria↗
PubMed1998

Secretory cell types and cell proliferation of human bronchial epithelial cells in an organ-culture system.

To study the secretory products and the proliferation of cells of the human respiratory surface epithelium, we established a miniorgan-culture system of bronchial tissue. Biopsies of large airways were grown on agar-coated dishes immersed in a serum-enriched medium. As determined by light and transmission electron microscopy, between 1 and 3 weeks, the organ cultures were covered by a differentiated epithelium consisting of secretory, ciliated, and basal cells. Immunohistochemistry, using antibodies to mucin and lysozyme, and lectin histochemistry revealed both mucous and serous secretory cells in the epithelium. Cell proliferation was studied in situ using antibodies to proliferating cell nuclear antigen (PCNA) and Ki-67. Whereas at the time of explantation the proliferation was low (2.5+/-1.7% of the epithelial cells were PCNA-positive, 1.7+/-0.6 were Ki-67-positive), at 24 h of cultivation, 30.4+/-5.1% or 25.2+/-4.9% of the epithelial cells were labeled with antibodies to PCNA or Ki-67. After 7 days, the number of dividing cells was low again. The results show that the organ-culture system of human respiratory surface epithelium produces a differentiated epithelium that is useful in the study of secretory processes, differentiation, and proliferation.

Bronchi↗
PubMed1975

Relation of cell type and cell density to the degree of post-transcriptional modification of tRNALys and tRNAPhe.

An examination of the reversed-phase chromatographic profiles of tRNALys and tRNAPhe from SV40-transformed BALB/3T3 cells grown to different cell densities, untransformed BALB/3T3 cells grown to confluency and BALB/c mouse liver indicates that with increasing cell density in culture the degree of the peroxy-Y modification in tRNAPhe and an undetermined modification in tRNALys become more like that of differentiated tissue (liver). Because precursor/product relationships appear to exist among the unmodified and modified forms of the isoaccepting species for each of these tRNAs, the present findings support the view that the often reported differences in tRNA isoaccepting spectra result primarily from differences in post-transcriptional modifications, rather than from different tRNA transcripts.

Cell Count↗
PubMed1999

Inhibition of T helper cell type 2 cell differentiation and immunoglobulin E response by ligand-activated Valpha14 natural killer T cells.

Murine Valpha14 natural killer T (NKT) cells are thought to play a crucial role in various immune responses, including infectious, allergic, and autoimmune diseases. Because Valpha14 NKT cells produce large amounts of both interleukin (IL)-4 and interferon (IFN)-gamma upon in vivo stimulation with a specific ligand, alpha-galactosylceramide (alpha-GalCer), or after treatment with anti-CD3 antibody, a regulatory role on helper T (Th) cell differentiation has been proposed for these cells. However, the identity of the cytokine produced by Valpha14 NKT cells that play a dominant role on the Th cell differentiation still remains controversial. Here, we demonstrate by using Valpha14 NKT-deficient mice that Valpha14 NKT cells are dispensable for the induction of antigen-specific immunoglobulin (Ig)E responses induced by ovalbumin immunization or Nippostrongylus brasiliensis infection. However, upon in vivo activation with alpha-GalCer, Valpha14 NKT cells are found to suppress antigen-specific IgE production. The suppression appeared to be IgE specific, and was not detected in either Valpha14 NKT- or IFN-gamma-deficient mice. Consistent with these results, we also found that ligand-activated Valpha14 NKT cells inhibited Th2 cell differentiation in an in vitro induction culture system. Thus, it is likely that activated Valpha14 NKT cells exert a potent inhibitory effect on Th2 cell differentiation and subsequent IgE production by producing a large amount of IFN-gamma. In marked contrast, our studies have revealed that IL-4 produced by Valpha14 NKT cells has only a minor effect on Th2 cell differentiation.

Animals↗
PubMed1978

Relation of cell type and cell density in tissue culture to the isoaccepting spectra of the nucleoside Q containing tRNAs: tRNATyr, tRNAHis, tRNAAsn and tRNAAsp.

An examination, using reversed-phase chromatography and cyanogen bromide treatment, of tRNATyr, tRNAHis, tRNAAsn, and tRNAAsp from SV40-transformed mouse fibroblasts grown to different cell densities, untransformed cells grown to confluence, and mouse liver indicates that: (1) The tissue cultured mouse fibroblasts examined here are hypomodified with respect to nucleoside Q, while liver tRNA is almost completely modified with respect to Q. (2) Cell density and/or proliferative state do not present as major variables in controlling the expression of Q in the present system. (3) SV40 virus transformation is not a major variable controlling the expression of Q in the present system. The present results support previous use of cyanogen bromide effected shifts in chromatographic elution as an assay for nucleoside Q.

Asparagine↗
PubMed1980

Papillary carcinoma of the thyroid, oxyphil cell type, "clear cell" variant: a light- and electron-microscopic study.

A unique case of papillary carcinoma of the thyroid having the combined features of three morphological subtypes--tall cell, clear cell and Hürthle cell--has been studied by light and electron microscopy. The distinctive neoplastic cells had an oxyphilic basal zone, a mid-placed nucleus and a clear apical region. Ultrastructurally, the cytoplasm was virtually filled with mitochondria, characteristic of Hürthle cells, but the unusual finding was the marked distention and emptiness of those mitochondria located in the apical zone, accounting for the clear phenomenon noted by light microscopy. In contrast, the mitochondria in the basal, or oxyphilic, part of the cells were intact. While a few cases of clear cell and papillary clear-cell carcinoma of the thyroid have been studied by electron microscopy previously, the clear change has never been attributed to dilated mitochondria, but rather to the presence of glycogen. The reason for the mitochondrial swelling is not answered, but it is probably an in vivo effect. Some of the other characteristics of papillary carcinoma of the thyroid described previously, such as microvilli, absence of colloid, infolded nuclei and nuclear bodies, were also present in this case. However, ground-glass nuclei, a frequently reported feature, were not found.

Carcinoma, Papillary↗
PubMed2002

Novel characterization of MHC class II-negative population of resident corneal Langerhans cell-type dendritic cells.

PURPOSE: The presence of antigen-presenting cells (APCs) such as Langerhans cells (LCs), an epithelial form of dendritic cells (DCs), in corneal tissue is critical for generation of immune responses, including graft rejection and herpetic keratitis. The purpose of this study was to characterize the distribution and major histocompatibility complex (MHC) antigen expression of corneal LCs. METHODS: Normal and inflamed corneas were excised from BALB/c mice, and immunofluorescence staining for CD11c, CD11b, CD45, CD80 (B7.1), CD86 (B7.2), CD3, and MHC class II (Ia) was performed by confocal microscopy on wholemount corneal epithelium. RESULTS: CD11c(+) MHC class II-positive LCs were found in the limbus and corneal periphery, but not in the center of the normal cornea. These cells were CD45 positive, exhibiting bone marrow derivation, and CD3 and CD11b negative, confirming a DC lineage. Additionally, these cells were CD80 and CD86 negative, reflecting an immature phenotype. In the central and paracentral areas, however, significant numbers of CD11c(+) LCs were detected that expressed no MHC class II. It is important to note that although the density of the LCs declined from the limbus toward the center of the cornea, they were always present. In the inflamed cornea, the expression of MHC class II and costimulatory molecules CD80 and CD86 was significantly enhanced, and present in all parts of the cornea, in contrast to the normal cornea. CONCLUSIONS: The present study demonstrates for the first time the phenotype and distribution of MHC class II-negative LCs in the murine corneal epithelium. In the inflamed cornea, the LCs become activated as reflected by expression of B7 costimulatory markers. These changes in activation markers may provide additional information for devising novel immunomodulatory strategies.

Animals↗