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At least 559 records · Page 31Linked to original sources
PubMed1981

Clonal analysis of the BALB/c T cell proliferative response to apo beef cytochrome c.

Murine T cell clones that proliferated specifically in response to the protein antigen apo cytochrome c were derived and maintained in continuous culture. Two distinct clonotypes were observed with respect to the proliferative responses observed when a variety of peptides prepared from several species of cytochrome c were tested. These 2 clonotypes appeared to recognize 2 different regions in the cytochrome c molecule. Only 1 of the 2 clonotypes tested demonstrated helper cell activity for antibody formation in vitro.

Animals↗
PubMed1983

Characteristics of tolerance induction among adult hapten-specific T lymphocyte precursors revealed by clonal analysis.

Thaptens 2,4,6-trinitrobenzene sulfonic acid (TNBS) and 3-iodo-4-hydroxy-5-nitrophenyl-acetic acid succinamide ester (NIP) on murine splenic and thymic cytotoxic T lymphocyte precursors (CTLp) was studied. Both BALB/c (H-2d) and CBA (H-2k) CTLp can be rendered unresponsive to subsequent in vitro stimulation with either hapten, provided the mice were pretreated with the correct dose of reactive hapten. The unresponsiveness was shown not to be due to toxicity, because treated animals can mount an alloreactive response equivalent to untreated animals. A degree of cross-reactivity in tolerance induction, however, was demonstrated between the two different haptens. Limit dilution analysis of tolerant lymphoid populations reveals that such cells obey single hit (zero order) kinetics and that there is effective deletion of the CTLp. After correction for "anti-self" responses, the anti-TNP CTLp frequency in TNBS-treated BALB/c mice was 10.7 X 10(-6) in contrast to 101.1 X 10(-6) in control animals (89.4% tolerance). Similarly, after correction for "anti-self" responses, the anti-NIP CTLp frequency in NIP-treated animals was 4.7 X 10(-6), in comparison to 42.8 X 10(-6) in control animals (89.0% tolerance). Kinetic studies show that tolerance occurs within 24 hr. This, together with the limit dilution data, argues against the role of suppressor cells, over the cellular range studied.

Animals↗
PubMed1984

[Clonal analysis of the intercellular variability in the functioning of human chromosomal nucleolus organizer regions].

Intercellular variability of NOR activity detected with the aid of Ag-staining of human chromosomes was studied in mass and cloned fibroblast cultures obtained from 3 individuals. The intercellular variability was determined by different staining of one of 10 NORs. According to this trait the heterogeneity of the cell population was discovered in all cloned lines, with this heterogeneity being the same as in the parent cultures. That concerned the number of a variable chromosome and the percentage of the cells with Ag-stained and unstained chromosomes. It is suggested that genetic determination in the progenies of the somatic cells concerns the whole spectrum of potential variability observed in cell populations.

Adult↗
PubMed1981

A general cell marker for clonal analysis of Drosophila development.

The mitochondrial enzyme, succinate dehydrogenase, can be localized by specific histochemical stains. A naturally occurring variant which gives heat-labile enzyme is used to map a gene responsible for succinate dehydrogenase. New alleles at the sdh locus are produced by mutagenesis and most of these are found to be homozygous lethal to flies. However, clones of cells which are homozygous for the new alleles can be produced by mitotic recombination, and are found to develop normally. If the chromosome arm bearing an sdh allele also carried brown, clones can be found in the eye. At the border of the clone the brown and sdh phenotype coincide showing that the sdh phenotype is expressed as a cell autonomous marker. Clones of sdh have been observed in the adult epidermis, the muscles, the gut, the heart and oenocytes where they display a clear phenotype. This new marker may be useful in studying the development of the internal organs of Drosophila.

Alleles↗
PubMed1980

Production, expansion, and clonal analysis of T cells with specific HLA-restricted male lysis.

A cytotoxic T cell (CT) lines grown as a population (CT line) was initiated from the peripheral blood lympocytes (PBL) of a female aplastic anemia patient who was known to express CT that were able to lyse HLA-A2-positive male cells. The anti-H-Y HLA-A2-restricted cytotoxic activity could be maintained over prolonged periods of time. The CT lines could be expanded and maintained in culture for >65 d by the use of mitogens and irradiated feeder cells. Out of 68 cultures obtained after cloning of the CT lines, 43 showed varying, but always specific, anti-H-Y HLA-A2-restricted lytic capacity on a per-cell basis. We could show that the cloned cultures were composed of >80% T cells that carry the HLA-A, -B, -C, and also the HLA-DR antigens identical to the original PBL.

Anemia, Aplastic↗
PubMed1981

Clonal analysis of the response of human myeloid leukemic cell lines to colony-stimulating activity.

The recent development of two continuously proliferating human myeloid leukemic cell lines (HL-60 and KG-1) that response to CSA provides an opportunity for a detailed study of the interaction of CSA with leukemic myeloid cells. Here we report on the colony-forming ability of HL-60 and KG-1 over an extended culture life of the cells. Several different sources of human CSA of different stages of purity enhanced colony formation of these cells. CSA, obtained from conditioned media from an SV-40 transformed human trophoblast, was partially purified, and its activity for normal bone marrow copurified with the activity that stimulated HL-60 colony formation. Over 100 clones of HL-60 were developed and tested for their response to CSA. All responded to CSA by showing an increase in colony size and number. However, none of the colonies formed from any of the 100 clones differentiated in response to CSA despite the fact that many chemical can induce differentiation of HL-60. since HL-60 forms spontaneous colonies without the addition of any exogenous stimulating factors, HL-60 conditioned media and cell extracts were tested for the production by these cells of their own endogenous growth-promoting activity (such as a CSA-like molecule). No growth-promoting endogenous activity was found that stimulated normal bone marrow or HL-60 colony formation even after concentration and fractionation methods were employed. These experiments suggest that: (1) the effect of CSA markedly favors proliferation over differentiation in these cell lines; (2) CSA is unlikely to suppress growth of the age of the type of leukemic myeloid cells that HL-60 and KG-1 represent; and (3) if HL-60 cells produce their own growth-promoting factor it is not detectable in the media.

Cell Line↗
PubMed1982

[clonal analysis of the independence of tumor cell multiplication from the substrate].

The clone of near-diploid mouse transformed CAK-25AGr cells is characterized by the stable cloning efficiency in a semi-solid medium (about 10(-5) per cell plated in methylcellulose). It was shown that colonies in the semi-solid medium were formed by rare single cells and did not arise as a result of slow multiplication of all cells in the population. These cells are not genetical variants different from other cells in the culture. This is assumed on the basis of following data. First, the majority of the subclones arising in methylcellulose (9 of 12) retained parental cloning efficiency in the semi-solid medium. Second, all 6 subclones picked from the solid substratum had the ability to form colonies in methylcellulose with the frequency not lower than that of the parental clone. Apparently, the proliferation in methylcellulose of the transformed cells studied is a stochastic process. Each cell in the culture has the ability to initiate a colony in the semi-solid medium with the certain probability. This probability is a heritable characteristic of the cloned cell line. It is possible that this characteristic reflects the norm of reaction of the cells to some environmental factors.

Animals↗
PubMed1995

Cytogenetic clonality analysis in myelodysplastic syndrome: monosomy 7 can be demonstrated in the myeloid and in the lymphoid lineage.

Bone marrow and blood from three patients with myelodysplastic syndrome (MDS) and monosomy 7 were studied for cell lineage involvement of the chromosomal abnormality. Cytogenetic involvement of the myeloid and erythroid cell lineages in MDS with monosomy 7 has been shown before. Lymphoid subpopulations have also been investigated but generally with negative results. A combined technique of May-Grünwald-Giemsa (MGG) for cell cytology and interphase fluorescence in situ hybridization (FISH) using a chromosome 7 specific DNA probe was applied. Further, immunophenotype and genotype of the cells were simultaneously examined with alkaline phosphatase anti-alkaline phosphatase (APAAP) immunostaining and FISH. The monosomy 7 was found in the blasts and in all or in subpopulations of myeloid and erythroid cells. T cells (CD3+, CD5+) did not appear to be involved. B cells (CD19+, CD22+) showed a normal distribution of FISH spots in two patients. In one patient however the loss of a chromosome 7 was found in approximately 70% of the cells positive for B cell markers including CD79a. The results of this study show that in some cases MDS is a disease arising in a progenitor cell with repopulative abilities restricted to myelopoiesis and erythropoiesis. In other cases, the pluripotent progenitor cells in MDS may show the capacities to differentiate into B lineage lymphoid cells, as well as suggesting that in those instances MDS represents a condition of more primitive transformed hematopoietic ancestor cells.

Adult↗
PubMed1995

Polyclonal and clonal analysis of human CD4+ T-lymphocyte responses to nut extracts.

The induction of IgE antibodies to aeroallergens depends upon antigen-specific CD4+ helper T cells of an 'interleukin-4 (IL-4)-dominant' phenotype. Nuts also drive IgE-mediated hypersensitivity and are the most dangerous of the orally encountered allergens. We have studied the polyclonal T-cell responses of atopic and non-atopic individuals to extracts of peanut, brazilnut and hazelnut. Strong proliferative responses were observed in all patients but specific IgE was only present in the nut-allergic patients suggesting a similar pathogenic mechanism to aeroallergen-mediated hypersensitivity. To investigate this hypothesis a panel of peanut-reactive T-cell clones was raised from a peanut- and brazilnut-allergic individual without hazelnut allergy. The antigen specificity, major histocompatibility complex (MHC) class II restriction and cytokine profiles of the T-cell clones were determined. With the exception of one T-cell clone, which proliferated in response to both peanut and hazelnut extract, the peanut T-cell clones were not cross-reactive with hazelnut or brazilnut. The T-cell clones recognized antigen in association with HLA-DR and HLA-DP but not HLA-DQ class II molecules. The peanut-specific clones produced high levels of IL-4 and low levels of interferon-gamma (IFN-gamma), exhibiting the 'TH2-like' profile which dominates the aeroallergen response. In contrast, the T-cell clone that was cross-reactive on both peanut and hazelnut allergen had a Th0-like phenotype, consistent with the lack of specific serum IgE to hazelnut. These results support the importance of functionally distinct T-cell populations that recognize oral allergens. The relative production of IL-4 and IFN-gamma of the cloned T cells in the peanut-allergic patients plays a role in determining whether or not IgE antibody responses are induced with the associated potential to develop anaphylactic reactions.

Adult↗
PubMed1994

Clonality analysis of B-cell lymphoma in fresh-frozen and paraffin-embedded tissues: the effects of variable polymerase chain reaction parameters.

To investigate the sensitivity of polymerase chain reaction (PCR)-based detection of B-cell monoclonality and the effects of several variables, we analyzed 119 cases of B-cell lymphomas with proven IgH gene rearrangements, testing fresh-frozen and formalin-fixed materials in parallel. Using fresh-frozen tissue, 83 cases (70%) were positive with one-step PCR and high-stringency annealing. Two groups of false-negative cases were identified, Group I (16 cases) showing no PCR products, and Group II (20 cases) showing polyclonal smear patterns. Seminested PCR and/or lowered annealing stringency revealed nine additional positive cases in Group I but none in Group II. Amplification with bcl-2/JH primers resulted in five more positive cases. The overall positive rate in the fresh-frozen category was 81% (97 of 119). Parallel analysis was performed on formalin-fixed, paraffin-embedded material from 61 cases, and a high concordance rate (89%) was observed. The results indicated that fresh and formalin-fixed specimens are comparable in this PCR-based assay, and that the two groups of false-negative results can be accounted for by different reasons. In addition, we reviewed the current literature, discussed the diagnostic applications of this technique, and listed the core elements of a proposed PCR protocol that should be suitable for most laboratories.

Base Sequence↗
PubMed1975

[Clonal analysis of the progeny of UV-irradiated Bacillus subtilis (uvr+ and uvr-) cells].

The revertants to adenine prototrophy or mutants to auxotrophy can be easily identified on synthetic media which are partly enriched by caseine hydrolysate and yeast extract. It is shown with the use of these media that 1.5% colonies formed by Bacillus subtilis cells of the original type (ade6 met5) have mutant clones which are initiated by spontaneous revertants to adenine prototrophy. These revertants arise in the time of division of cells in macrocolonies. After plating diluted suspension of irradiated cells those colonies which contain mutant clones formed by spontaneous revertants can be erroneously taken for mixed colonies formed by induced revertants. About 40% mutants to auxotrophy induced by high dose of UV-light in in uvr+ cells form pure mutant colonies. The same mutants, induced by uvr cells by five time less UV-dose, usually form mixed colonies.

Adenine↗
PubMed1994

Clonal analysis of rat tibia growth plate chondrocytes in suspension culture--differential effects of growth hormone and insulin-like growth factor I.

The number of growth hormone (GH) receptors in cultured rat epiphyseal chondrocytes are increased with numbers of cell divisions in monolayer. We wanted to study if increased number of cell divisions in monolayer influence GH or insulin-like growth factor I (IGF-I) response in a subsequent suspension culture. Primary isolated chondrocytes from rat tibia growth plates were cultured in monolayer at different seeding densities (4000, 8000 and 24,000 cells/cm2). After a culture period of 7 days, cells were trypsinized, counted and subcultured at 50,000 cells per dish in suspension stabilized with 0.5% agarose. 14 days later the agarose cultures were dried, stained and the number of clones with a diameter exceeding 50 microns was counted. Individual clones were classified as undifferentiated or differentiated according to the following criteria: cell clusters with a diameter of 50 microns and without matrix staining were classified as undifferentiated; cell clusters with a diameter over 50 microns consisting of 4 cells or more and with matrix stained by Alcian Blue were classified as differentiated clones. Human growth hormone (hGH) added to the suspension culture medium increased the number of undifferentiated clones if cells had been precultured at 4000 and 8000 cells/cm2 but hGH had no stimulatory effect on either clone type at 24,000 cells/cm2. IGF-I significantly increased the number of differentiated clones at all seeding densities while no effect was demonstrated on the number of undifferentiated clones. The results from the present study suggest that an increased number of cell divisions during primary monolayer culture increases GH responsiveness in a subsequent suspension culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗