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M C Mingari

Publications and source records attributed to M C Mingari.

137 records · Page 8Linked to original sources
PubMedDate not supplied

Recent progresses in the phenotypic and functional characterization of human cytolytic T lymphocytes.

Over the past several years, a number of major advances have been made in our understanding of the phenotypic and functional heterogeneity of human T lymphocytes. Most of these advances have resulted from: 1. the availability of monoclonal antibodies directed to T cell surface antigens; 2. the development of sensitive microassays to measure lymphocyte function in vitro; 3. the refining of T cell cloning technology. The most relevant studies in delineating how human T cell functions have been based on the analysis of T cell clones with specific cytolytic activity. These studies allowed the recent molecular definition of structures serving as specific antigen receptor on T cells as well as the understanding of the role of accessory molecules involved in specific receptor activity such as T3, T8 and T4 antigens. The development of microculture conditions allowing clonal proliferation of all human T lymphocytes, whether resting or activated, has provided a major tool for the precise definition of the frequency and subset distribution of T cells with different functional capabilities. Studies along this line have shown that precursors of cytolytic T lymphocytes (CTL-P) represent about one third of peripheral blood human T lymphocytes; in addition, all T8+ were CTL-P, whereas CTL-P were relatively rare among normal T4+ lymphocytes. As much as 20% cytolytic T lymphocytes were found to be capable to release interleukin-2 and B cell growth factor, thus indicating that cytolytic and helper function may be associated at the single cell level.

Antibodies, Monoclonal↗
PubMedDate not supplied

Surface markers of human T lymphocytes.

Surface markers have been extensively used for the identification and fractionation of different sets of human lymphocytes. Although they have proven useful for the identification of different cell subpopulations and for delineating various stages of T cell maturation or activation, there are a number of limitations in their application that should be carefully considered. In most instances, markers which are reported as defining functional subpopulations are not directly involved in the functional capability to be defined. In addition, a precise correlation between surface markers and cell function is difficult if only a small percentage of the cells in a given subset is involved in the functional activity measured. It is also clear that cell activation and differentiation, or mechanisms of cell fractionation, may affect the expression of some surface markers. Moreover, the assumption that functional activities ascribed to cell subsets or to surface markers in vitro are also operating in vivo may be incorrect. Human T cell surface markers can be grouped in various (as well as overlapping) categories, namely those recognizing the total T cell population, those present on T cell subsets and those expressed only on T cells at a given stage of maturation or as a consequence of cell activation. A more precise correlation between the presence of surface markers and the expression of functional activities can be performed by more complex experimental approaches such as the combined use of various markers and the analysis of surface phenotype of T cell clones with defined functional properties. While the study of T cell clones has clearly pointed out the inadequacy of most markers commonly used for identifying functional subsets of T cells, it provides a valuable tool for identifying new markers that may indeed be selective for a given T cell function.

Antibodies, Monoclonal↗
PubMedDate not supplied

Analysis of CD3-associated molecules in CD4- 8- human T cell clones lacking the typical alpha/beta T cell receptor.

Four clones were isolated from CD3+ 4- 8- normal peripheral blood T lymphocytes. They lacked expression of the typical alpha/beta T cell receptor, as assessed by reactivity with the WT31 monoclonal antibody (mAb) recognizing a non-polymorphic structure of the alpha/beta heterodimer. All the four clones lysed the natural killer-sensitive K562 target cells and released interleukin-2 following stimulation with phytohemagglutinin. After cell treatment with the cross-linking agent dithiobis-succinimidyl-propionate, molecules immunoprecipitated with an anti-CD3 mAb were represented by a major 45-kD and a minor 43-kD band. These molecules were different from typical alpha/beta molecules and are likely to represent the molecular product of the human gamma gene.

Antigens, Differentiation, T-Lymphocyte↗
PubMedDate not supplied

Interleukin-2-induced proliferation of CD4-CD8- human thymocytes. In vitro expression of CD3 and CD8 antigens and cytolytic activity.

Human thymocytes lacking both CD4 and CD8 differentiation antigens were prepared by treating total thymocyte suspensions with a mixture of anti-CD4 and anti-CD8 monoclonal antibodies and complement. The resulting populations contained less than 2% CD4+, CD8+ or WT31+ cells and variable percentages (less than 20%) of CD3+ cells. These cell populations were cultured in recombinant IL-2 in the presence of peripheral blood mononuclear cells as feeder cells. Cells underwent extensive proliferation accompanied by a progressive increase of CD3+ and CD8+ cells. On the other hand, appearance of neither WT31+, alpha/beta-positive T cell receptor (TCR), nor CD4+ cells could be observed in several independent experiments. Functional analyses revealed the appearance and the progressive increase of cytolytic activity against the natural killer (NK)-sensitive K562 cells as well as the NK-resistant fresh melanoma cells. Experiments of T cell cloning indicated that both the expression of CD8 and CD3 antigens and the appearance of cytolytic activity were consequent to cell maturation occurring at the level of CD4-CD8- non-cytolytic cell precursors. In these experiments, more than 30% of cells underwent clonal expansion and all the clonal progenies obtained displayed cytolytic activity and expressed the CD3+WT31- surface phenotype. The expression of CD8 was variable, whereas no CD4+ clones could be obtained. Cells expressing such surface phenotype are known to belong to the TCR gamma-positive T lymphocyte subset lacking the typical alpha/beta TCR and thus appear to be the only T cell type capable of in vitro proliferation and maturation under easily reproducible culture conditions.

Antigens, Differentiation, T-Lymphocyte↗
PubMedDate not supplied

Phenotypic and functional heterogeneity of human T cell clones producing gamma-interferon.

Human T cell clones were derived from peripheral blood and screened for their ability to release gamma-interferon (gamma-IF) following PHA stimulation. Nine clones producing more than 20 U/ml of gamma-IF were expanded and analyzed for cytolytic activity in a lectin-dependent assay and for the ability to release interleukin-2 (IL-2). In addition, clones were analyzed for T4 and T8 antigen expression. Five out of nine clones had cytolytic T lymphocyte activity, while four released relatively large amounts of IL-2. Five clones were T4+ while the remaining expressed the T8+ phenotype. These results clearly indicate that gamma-IF production is not restricted to T cell subsets defined according to either functional or phenotypic criteria.

Clone Cells↗
PubMedDate not supplied

Human interleukin-2 promotes proliferation of activated B cells via surface receptors similar to those of activated T cells.

Human interleukin-2 (IL-2) is a glycoprotein of relative molecular mass (Mr) 15,000, which is released by T lymphocytes on stimulation with antigen or mitogen and functions as a T-cell growth factor (TCGF) by inducing proliferation of activated T cells. It is generally accepted that resting or activated B cells do not respond directly to IL-2 but require for their proliferation other T-cell-derived lymphokines usually referred to as B-cell growth factors (BCGFs). Recently, however, a monoclonal antibody reacting with the IL-2 receptor molecules expressed by activated T cells (anti-Tac) was shown to react also with certain B tumour cells; in addition, murine B cells proliferate in response to pure human IL-2. We now show that recombinant IL-2, derived from Escherichia coli expressing the human gene, is able to promote strong proliferation of human B cells activated with protein-A-rich Staphylococcus aureus Cowans strain I. Moreover, we demonstrate that the anti-Tac antibody also reacts with S. aureus-activated normal B cells and inhibits sharply the proliferative response of such cells to IL-2. Finally, immunoprecipitation experiments reveal that anti-Tac defines similar molecules on activated T and B cells.

Animals↗
PubMedDate not supplied

Phenotypic and functional characterization of human T lymphocytes expressing a gamma/delta T cell antigen receptor.

Most mature T lymphocytes express CD3-associated antigen receptor molecules (TCR) formed by alpha and beta chains. Recently, a minor subset has been identified that express a different CD3-associated TCR composed of gamma and delta chains. The cell subset expressing TCR gamma/delta differs from conventional T cells in a number of phenotypic and functional characteristics. The simultaneous lack of both CD4 and CD8 antigens at the cell surface allows one to greatly enrich for TCR gamma/delta + cells (by monoclonal antibodies, mAbs and complement). Cloning of CD4-8- peripheral blood lymphocytes revealed that they are homogeneously composed of cytolytic cells which, in most instances, lyse tumor target cells. TCR gamma/delta + cells proliferated in response to allogeneic cells in mixed lymphocyte culture (MLC) and MLC-derived TCR gamma/delta + cells specifically lysed PHA-induced blast cells bearing the stimulating alloantigens, thus providing the formal proof that they recognize (allo)antigens. The use of different mAbs specific for TCR gamma/delta molecules allowed us to identify two distinct subsets which bound BB3 and delta-TCS-1 mAbs, respectively. The BB3-reactive molecules in peripheral blood-derived TCR gamma/delta + cells were represented by C gamma 1-encoded disulphide-linked heterodimers, whereas delta-TCS-1 reacted with C gamma 2-encoded non disulphide-linked molecules. Both BB3 and delta-TCS-1 mAb induced activation of cloned cells expressing the corresponding antigenic determinants (as assessed by measurements of intracellular Ca++ and/or lymphokine production or cytolytic activity).(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗