PubMed Health⌕ Search

Biomedical subjects

A Zicca

Publications and source records attributed to A Zicca.

At least 37 records · Page 2Linked to original sources
PubMed1988

Coculture of human keratinocytes and melanocytes: differentiated melanocytes are physiologically organized in the basal layer of the cultured epithelium.

Human epidermal keratinocytes differentiate in vitro into a stratified epithelium suitable for grafting on burned patients. In this paper, we show that differentiated melanocytes are present in the cultured epithelium. In particular, we have found that i) melanocytes proliferate in the same culture conditions that allow keratinocyte growth, ii) during the culture the ratio between keratinocytes and melanocytes tends to remain constant, iii) melanocytes organize into the basal layer of the cultured epithelium independently of the presence of dermis, develop dendritic arborizations with melanosome-containing processes and transfer melanosomes into keratinocyte cytoplasm.

Cell Differentiation↗
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↗
PubMed1984

Granule formation in large granular lymphocytes (LGL). Ultrastructural and cytochemical studies on cells from patients with abnormally expanded lgl populations.

The peripheral blood mononuclear cells from five patients with abnormally expanded populations of large granular lymphocytes (LGL) of possible malignant origin have been studied by electron microscopy. These cells had fewer granules than normal circulating LGL but displayed a variety of organelles possibly involved in the process of granule formation. This process apparently originated from the fusion of vesicles that had a characteristic cup-shape (and appeared to be derived from the Golgi apparatus) with smaller vesicles, mostly of the coated type. This fusion resulted in the formation of multivesicular bodies (MVB) whose limiting membrane was constituted by that of the cup-shaped vesicle. MVB gradually matured into electron-dense granules. A number of cup-shaped vesicles were found positive for the cytochemical localization of thiamine pyrophosphatase (TPP) activity that is a specific marker of the trans aspect of the Golgi apparatus, a finding which confirmed that they were Golgi-derived. The smaller, mostly coated, vesicles were positive for acid phosphatase (AP) and evidence was obtained indicating that they subserved the function of transporting acid hydrolases from the rough endoplasmic reticulum to the cup-shaped vesicles or to the MVB. The plasma membrane did not appear to contribute to MVB or granule formation since endocytic vacuoles induced by reacting the cell surface with the appropriate monoclonal antibodies (followed by peroxidase labelled anti-immunoglobulin) were never seen while fusing with granules or MVB. Rather, these vesicles formed secondary lysosomes after having encountered smooth or, more rarely, coated vesicles. Granulogenesis in LGL, therefore, resembles the process of granule formation observed in secretory cells. The active process of granulogenesis detected in the patient cells and a number of other findings indicate that they were LGL at early stages of maturation. The surface phenotype consistently found in these cells (OKT3+, Leu 1+, OKT8+, Leu 2a+, OKT11+, Leu 5+ and OKM1) is different from that of the majority of the normal LGL and may correspond to that of immature LGL.

Acid Phosphatase↗
PubMed1983

Ultrastructural characteristics of human T cell clones with various cytolytic activities.

Fifteen T cell clones with different (specific, antibody-dependent or natural killer-like) cytolytic activity were derived from mixed lymphocyte culture activated T cells and analyzed for their morphological characteristics and, in some instances, for their surface markers. All of the five cytolytic clones analyzed by electron microscopy possessed numerous electron-dense granules and in some instances multivesicular bodies, with or without an electron-dense matrix, that are the putative precursors of the granules. In addition, light microscopy examination of semithin sections of other ten cytolytic clones showed that the large majority of the cells in each clone had numerous toluidine blue-stained cytoplasmic granules. It is of note that nine clones without detectable cytolytic activity analyzed by electron microscopy did not possess granules and presented the features of large agranular blasts. Ten cytolytic clones were analyzed for different surface markers including rosette formation with sheep erythrocytes (E rosettes), receptors for the Fc portion of IgG or IgM ((Fc gamma R and Fc mu R) and a group of antigens recognized by monoclonal antibodies including Ia, 4F2, OKT8 or OKT4. All the clones were E-rosette+, Ia+ and 4F2+. Expression of Fc gamma R was restricted to the clones active in antibody-dependent cell-mediated cytotoxicity. Expression of OKT8 and OKT4 antigens was variable; in particular, five clones were OKT8+/OKT4-, whereas the other five expressed the OKT8-/OKT4+ phenotype. It is noteworthy that the ultrastructural features of cytolytic T cell clones are similar to those of large granular lymphocytes, known to be the only lymphoid cells in normal peripheral blood which possess cytolytic activity. Thus, it is possible that the presence of electron-dense granules may represent a morphological marker for all human cytolytic lymphocytes.

Antigens, Surface↗
PubMed1983

Expression of a receptor for sheep erythrocytes by B lymphocytes from a chronic lymphocytic leukemia patient.

A patient with a B-cell chronic lymphocytic leukemia, whose lymphocytes also formed rosettes with sheep red cells, is described. The B-cell nature of the malignant lymphocytes was determined by surface marker analysis, and cytochemical and ultrastructural studies. The lymphocyte membrane immunoglobulin (IgG1K) did not have anti-sheep red cell activity and was not responsible for the binding of sheep erythrocytes to the leukemic cells as shown by (i) the failure to inhibit rosette formation with anti-immunoglobulin reagents and (ii) the different sensitivity to proteolysis of the membrane immunoglobulin and the sheep erythrocyte receptor. The malignant lymphocytes expressed a receptor for sheep erythrocytes similar to that of normal T cells since they stained with monoclonal antibodies directed against the sheep red cell receptors. Furthermore these antibodies blocked rosette formation. Endogenous labeling experiments demonstrated that the patient's cells produced IgG both of the membrane and of the secretory type. The latter molecular form was also actively secreted. Ultrastructural studies demonstrated that the malignant clone comprised cells at different maturational stages and with different secretory properties. These findings were confirmed by the analysis of intracytoplasmic acid hydrolases, which are normally expressed at late maturational stages. These data are consistent with the hypothesis that a process of maturation was occurring within the malignant clone.

Aged↗
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

Differentiation of chronic lymphocytic leukemia cells: correlation between the synthesis and secretion of immunoglobulins and the ultrastructure of the malignant cells.

The capacity of synthesizing and secreting Ig molecules was studied in 11 patients with B-cell chronic lymphocytic leukemia (B-CLL) whose cells expressed surface IgM, in 3 patients with surface IgG-bearing cells, and in 2 IgM prolymphocytic leukemias (IgM-PLL). Three types of mu chains were detected by SDS-polyacrylamide gel electrophoresis analysis of the endogenously labeled molecules isolated by specific immunoprecipitation. Two of them were isolated from the cell lysates and were identified as the membrane mu chain and the precursor of the secreted molecules, respectively. The latter also possibly contained precursors of the membrane molecules. The third type of molecule was detected only in the culture medium and was identified as secretory mu chain. Not all of the malignant clones possessed the three types of mu chains. Only 7/13 of the IgM-bearing malignant cell clones were capable of secretion, whereas the remaining synthesized the secretory mu chains but degraded them intracellularly. Two types of molecules (membrane and secreted) were found in the IgG-bearing CLL cells from three patients. In all of them, secretion was detected. Ultrastructural analysis demonstrated that cells from the secreting clones had the features of more mature lymphocytes than the cells from nonsecreting clones. These features were represented by a developed Golgi apparatus, various types of vesicles (smooth and coated), and strands of the rough endoplasmic reticulum. A certain heterogeneity of the degree of maturation of the cells was observed within these clones. The data are consistent with the hypothesis that CLL clones are heterogeneous and can be distinguished through the different degrees of maturation of their cell components.

Antibodies, Anti-Idiotypic↗
PubMed1982

Immunofluorescent and ultrastructural analysis of plasma cell degeneration in the chicken Harder's gland.

In this study we describe some aspects of plasma cell degeneration in the chicken Harder's gland. The immunofluorescent patterns of cytoplasmic immunoglobulin (cIg) localization have been studied in relation to the ultrastructure of maturing and degenerating B cells. It appears that Russell body formation through the accumulation of Ig within the cisternae of the rough endoplasmic (RER) does not represent the only mechanism for the formation of cytoplasmic vacuoles. Mitochondrial swelling and disruption or dilation of Golgi cisternae, often preceding alterations of the RER, may be the origin of some vacuoles. It also appears that, in the Harder's gland, degeneration may occur not only in mature plasma cells but also in maturing B cells at a stage when only clusters of polyribosomes are found in the cytoplasm and no RER is yet developed. These observations are relevant to some immunofluorescence and ultrastructural patterns observed in human B-cell pathology.

Animals↗
PubMed1982

Receptors for the third complement component on a proportion of large granular lymphocytes from human peripheral blood.

Large granular lymphocytes (LGL) are nonadherent cells with cytoplasmic azurophilic granules, avid receptors for the Fc portion of IgG, and a paranuclear localization of alpha-naphthyl acid esterase or acid phosphatase. LGL constitute the bulk of TG cells (cells with receptors for sheep erythrocytes and for IgG molecules) and null cells (non-T, non-B cells). In the present study we demonstrate that 20-33% of the circulating human LGL express receptors for the third complement component (C3R). When TG cell or null cell fractions from normal individuals or non-T cells from a patient with infantile agammaglobulinaemia (which contained almost exclusively LGL) were rosetted with erythrocytes coated with antibody and complement, a variable number of C3R-bearing cells were detected. Such cells were isolated and analysed further; the great majority of them displayed the cytochemical and ultrastructural features of LGL.

Acid Phosphatase↗
PubMed1982

Acid hydrolases as markers of maturation in B-cell chronic lymphocytic leukemia.

Malignant lymphocytes from 30 B-cell chronic lymphocytic leukemia (B-CLL) patients were studied for the cytochemical localization of two acid hydrolases, alpha-naphthyl acetate esterase (ANAE) and acid phosphatase (AT). The large majority of the cells stained for both ANAE and AP in 7 cases, for AP only in 18 cases, and were negative for both the enzymes in 5 cases. Ultrastructural analysis revealed that the cells that displayed more mature morphological features, such as well developed smooth and rough membrane compartments, were those positive for acid hydrolases. That ANAE and AP are expressed by B cells at late stage of maturation was confirmed by the finding that some lymphocytes and all of the plasmacytoid lymphocytes and plasma cells from Walderström's macroglobulinemia, from mixed cryoglobulinemia, and from multiple myeloma patients stained strongly for both ANAE and AP. Using the expression of acid hydrolases and certain ultrastructural features as markers of cell differentiation, it was possible to demonstrate a process of maturation within the single B-CLL clones with accumulation of the cells at stages that differed in the various cases.

Acid Phosphatase↗
PubMed1982

Large granular lymphocytes in human peripheral blood: ultrastructural and cytochemical characterization of the granules.

Large granular lymphocytes (LGL) are defined as nonadherent mononuclear cells with cytoplasmic azurophilic granules, avid receptors for the Fc portion of IgG, and cytotoxic functions (NK or ADCC activities). In the present study, the granules of LGL isolated from human peripheral blood have been analyzed by enzyme cytochemistry and electron microscopy. It had been found that: (1) in the single cells, granules at different stages of maturation could be detected: in addition, packaging of the granules took place in the proximity of the Golgi apparatus, which is similar to that seen in secretory cell types. (2) Acid phosphatase (AP) was observed within the granules and the vesicles located in the Golgi area: the Golgi apparatus identified through its thiamine pyrophosphatase-positivity was consistently negative for AP. (3) Alpha naphthyl-acetate esterase (ANAE) activity was localized in the granules as well as on the membrane of LGL and monocytes. (4) The ANAE activity of LGL was of the monocytic and not of the lymphocytic type, as shown by NaF inhibition. (5) The LGL granules, although identifiable as primary lysosomes, were not involved in the process of phagocytosis, since LGL failed consistently to ingest latex particles or opsonized red cells.

Acid Phosphatase↗