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Biomedical subjects

A Nocera

Publications and source records attributed to A Nocera.

At least 73 records · Page 4Linked to original sources
PubMed1989

[Characterization with dithiothreitol (DTT) of IgM auto-lymphocytotoxic antibodies in dialyzed patients awaiting kidney transplants].

A group of 42 sensitized dialysis patients showing high reactivity (81%-100%) against a random panel of peripheral blood lymphocytes (PBL), were analyzed for the presence of autoreactive lymphocytotoxic antibodies. The test was performed at different temperatures (4 degrees C, 22 degrees C, 37 degrees C) with dithiothreitol (DTT) against autologous PBL, EBV-induced autologous B lymphoblasts (A-BCL), K562 cells and T lymphocytes. Thirteen of 42 patients had IgM auto-lymphocytotoxic antibodies. The broadly reactive IgM autoantibodies could be inactivated by treatment with DTT 5 mM and allowed the identification of the presence of autoantibodies alone or in combination with anti-IgG alloantibodies.

Autoantibodies↗
PubMed1987

Morphology, cytochemical features, and membrane phenotype of HLA-DR+ interstitial cells in the human pancreas.

The morphology, histological distribution, surface, and enzymatic phenotype of pancreatic HLA-DR+ cells were studied on seven human pancreata, removed from cadaver donors. Frozen and paraffin-embedded pancreas sections were stained with a battery of monoclonal antibodies by indirect immunofluorescence, immunoperoxidase, and immunophosphatase techniques. Two type of cells were found to express HLA-DR surface molecules: endothelial cells and nonfibroblastic non-B and non-T interstitial elements. The latter cells, which were localized both in the exocrine and endocrine portions of the organ, were distinguished in two main families (macrophagic and dendritic) according to their morphology, surface phenotype, and lysosomal enzymatic activities. The phenotype of cells belonging to macrophagic cell family was the following: Leu M1+, Leu M2+, Leu M3+, OKM1+, and OKT6-. In addition these cells were positive for the expression of lysosomal enzymes such as alpha-naphthyl acetate esterase (ANAE) and acid phosphatase (AP). The "dendritic" cell family comprised, among others, cells that were characterized by the presence of numerous finger-like projections, the absence of Leu M1, Leu M2, Leu M3, OKM1, OKT6 surface antigens, and by the negativity for ANAE and AP. These "dendritic looking cells" (DLC) constituted the most represented DR+ cell type within pancreatic islets. The demonstration of dendritic cells within human islets may justify, in humans also, in vitro procedures of intra-islet dendritic cell removal prior to transplantation, in the attempt of islet rejection prevention.

Dendritic Cells↗
PubMed1987

Identification of autoreactive lymphocytotoxic antibodies in sensitised dialysis and kidney transplant patients.

Autoreactive lymphocytotoxic antibodies, which have been found in sensitised dialysis patients, are generally not considered to be harmful to a renal allograft. In this work the presence of such autoreactive antibodies was investigated in the following groups of sensitised endstage renal disease patients: (a) dialysis patients waiting for a first kidney transplant, (b) kidney transplanted patients, and (c) dialysis patients with a previous failed graft. Only sera from the above patients which showed high reactivity (greater than 30%) against peripheral blood lymphocytes of a random cell panel (R-PBL), were screened for the presence of autoreactive lymphocytotoxic antibodies, by testing at different temperatures against autologous T lymphoblasts (PHA-ATL) and EBV-induced autologous B lymphoblasts (EBV-ABL). The results showed that both blood transfusions, and viral infections such as cytomegalovirus (CMV), correlated with the presence of autoreactive antibodies, and that in addition, by using PHA-ATL and/or EBV-ABL as absorbing reagents, it was possible to remove the antibodies. These absorption procedures allowed the identification of the presence of autoreactive antibodies alone or in combination with other alloantibodies.

Adolescent↗
PubMed1985

In vitro production of different interferon types by cloned human NK cells.

Human peripheral blood null cells were conjugated in vitro with K-562 cells and expanded into continuous cell lines using IL-2 containing medium (CM) and periodical restimulation with phytohaemagglutinin (PHA). Most of these lines were made up of granular blasts expressing high natural killer (NK) activity. When analysed for different surface markers, the large majority of the blasts were E rosette+, T3+, Tac+, DR+, Leu7+ with a variable proportion of cells expressing T8 and M1 antigens (range: 20-80%). In contrast, T4 antigen was expressed by the majority of cells of the control cell lines originated in the absence of K-562 cells. Twenty-nine clones were obtained from one of the above lines using the limiting dilution technique and subsequently maintained in CM for 4 months or more. The majority of these clones maintained their cytotoxic potential and were able to produce different interferon (IFN) types (IFN-alpha, IFN-gamma or both) when growing in CM. In addition in a number of selected clones, simultaneous stimulation with PHA and K-562 cells was able to induce or support the production of both IFN types.

Antigens, Surface↗
PubMed1985

Large granular lymphocytes have a promoting activity on human peripheral blood erythroid burst-forming units.

Peripheral blood mononuclear cells were fractionated according to the expression of a variety of surface markers, and the fractions obtained were tested for erythroid burst-forming unit (BFU-E) colony formation. BFU-Es were detected in the HLA-DR+ non-T cell fraction, but gave rise to optimum colony numbers only in the presence of a nonadherent, relatively radioresistant cell. This accessory cell was found among the HLA-DR- non-T, non-B cells, a fraction that was particularly enriched in large granular lymphocytes (LGLs). Experiments carried out to assess directly the surface markers of the accessory cell revealed an FcR+, OKM1+, Leu 7+, Leu 11+, OKT4-, OKT8- surface phenotype, which is consistent with that of the majority of LGLs. Peripheral blood LGLs, purified by Percoll density gradient, proved very efficient in promoting optimal BFU-E colony formation. All of these results indicate that LGLs have a potent erythroid burst-promoting activity. Such activity is probably mediated through the release of soluble factors, as shown by the observation that LGL culture supernatants were as effective as LGLs in sustaining colony formation.

Antigens, Surface↗
PubMed1983

Complement receptor distinguishes between two subsets of large granular lymphocytes with different natural killer activity and cytochemical and ultrastructural features.

Human peripheral blood large granular lymphocytes (LGL)--that is, cells with intracytoplasmic azurophilic (electron-dense) granules, with a positivity for the cytochemical localization of certain acid hydrolases, and with avid surface receptors for the Fc portion of IgG--have been purified on Percoll density gradients. Approximately 30% of these cells expressed receptors for the third complement component (C3R). They were separated into C3R-positive and C3R-negative cells. C3R+ cells had a significantly greater natural killer (NK) activity against K562 target cells than C3R+ cells. This difference was unrelated to the presence in the C3R+ cells of a contaminant cell type incapable of NK activity, since cytochemical and ultrastructural analysis revealed that C3R+ and C3R- fractions contained comparable LGL numbers. Agarose cytotoxicity assays at the single-cell level demonstrated that C3R+ LGL contained a large number of cells that bound to but did not lyse the target. The remaining fully cytotoxic C3R+ LGL had, however, the same killing and recycling properties as the cells from the C3R fraction. Electron microscopy and cytochemical studies showed that C3R+ cells had fewer electron-dense granules than C3R cells and stained more faintly for the localization of alpha-naphtyl acetate esterase. In contrast to C3R cells, C3R+ LGL displayed morphological features suggesting that an active process of granule formation was taking place. Taken together, the data indicate that C3R+ cells represent a discrete subset or a maturational stage of LGL.

Antibodies, Monoclonal↗
PubMed1983

Augmentation of human peripheral blood natural killer activity by methisoprinol.

Methisoprinol (MIP) was found to augment natural killer (NK) activity of peripheral blood mononuclear cells (PBMC), as measured in a 4-h 51Cr release assay using K562 cells as targets. Overnight incubation of PBMC with 0.1 microgram/ml MIP, followed by removal of the drug, resulted in significant increases in the NK activity of all 17 donors studied. Augmentation of NK, expressed as lytic units (LU)/10(7) effector cells, was generally two- to fourfold, and was manifest as early as 1 h after incubation with the drug, but was maximal after 4 h. The effect of MIP was dose dependent up to 0.1 microgram/ml and remained at a plateau up to 10 micrograms/ml, where cytotoxicity to the effectors was observed. The effect of MIP was exerted on the effector cells and was not due to an increased susceptibility of target cells to lysis. In addition, this phenomenon was probably independent of interferon (IFN) production. Binding and killing at the single-cell level were shown to be unaffected by prior treatment with MIP. Rather, the analysis of the kinetics of NK activity indicated that MIP increased the recycling ability of NK effector cells. Augmentation of NK by MIP was dependent on the presence of adherent cells in PBMC fractions. Populations depleted of plastic adherent cells or populations enriched for adherent cells themselves could not undergo boosting by MIP, indicating that MIP did not act to recruit functional cells from inactive precursors. These studies suggest that the observed antiviral and/or immunoregulatory actions of MIP might be mediated through an increased NK cell activity.

Cell Adhesion↗
PubMed1983

PHA-induced human T cell colony formation: enhancing effect of large granular lymphocytes.

The capacity of phytohemagglutinin (PHA)-stimulated human T cells to develop into colonies in agar has been evaluated in the presence or absence of a variety of peripheral blood mononuclear cell subsets. A subpopulation of non-T, non-B cells with receptors for the Fc portion of IgG (i.e. third population cells or TPC) was found to enhance considerably the T cell colony forming capacity. Since TPC have been previously shown to be highly enriched for large granular lymphocytes (LGL, i.e. cells with cytoplasmic azurophilic granules and acid hydrolases), LGL were purified on Percoll density gradients and tested for their T cell colony enhancing capacity. It was shown that LGL were indeed the cells capable of enhancing the T cell colony formation.

Cell Separation↗