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C Cabañas

Publications and source records attributed to C Cabañas.

49 records · Page 3Linked to original sources
PubMed1990

Phorbol esters induce differentiation of U-937 human promonocytic cells in the absence of LFA-1/ICAM-1-mediated intercellular adhesion.

Intercellular adhesions which occur during the mononuclear phagocyte differentiation are predominantly mediated by the lymphocyte-function-associated antigen-1 (LFA-1) family and the intercellular-adhesion molecule-1 (ICAM-1) which is a ligand for LFA-1. Thus, differentiation of U-937 promonocytic cells induced by phorbol esters occurs concomitantly with intercellular LFA-1/ICAM-1-dependent cluster formation. Since these homotypic adhesions can be inhibited by monoclonal antibodies (mAb) directed to either LFA-1 or ICAM-1, we have analyzed whether the lack of cell-cell adhesions impairs the differentiation process. Treatment of U-937 cells with the phorbol ester 12-O-tetradecanoylphorbol 13-acetate in the presence of mAb to LFA-1 or ICAM-1 antigens yielded cells free from homotypic adhesions but differentiated as evidenced by their decreased proliferation and enhanced capacity for generation of superoxide anion. In addition, expression of the CD11c antigen was increased, whereas the transferrin receptor disappeared from the cell surface. Vimentin gene transcription was also greatly augmented as opposed to a clear diminution in the levels of c-myc and ornithine decarboxylase transcripts. These results clearly demonstrate that phorbol esters can induce differentiation of monocytic cells independently of cell-cell adhesion.

Antibodies, Monoclonal↗
PubMed1990

The CD11c antigen couples concanavalin A binding to generation of superoxide anion in human phagocytes.

We have found that an anti-CD11c monoclonal antibody (MAb) inhibits the respiratory burst induced in phorbol 12-myristate 13-acetate (PMA)-differentiated U937 cells as well as in human peripheral blood monocytes and neutrophils upon cell stimulation with concanavalin A. The MAb had no effect, however, when the added stimulus was fMet-Leu-Phe or PMA. Flow cytometry analyses indicated that concanavalin A was able to interact with CD11c. The anti-CD11c MAb inhibited significantly concanavalin A binding to differentiated U937 cells, and concanavalin A blocked binding of anti-CD11c MAb to the cells. Binding of labelled concanavalin A to membrane proteins which were separated by PAGE and transferred to nitrocellulose paper indicated that proteins with apparent molecular masses similar to those of CD11c (150 kDa) and CD18 (95 kDa) molecules were the main concanavalin A-binding proteins in differentiated U937 cells as well as in mature neutrophils. Similar experiments carried out in the presence of the anti-CD11c MAb showed a specific and significant inhibition of concanavalin A binding to the CD11c molecule. These results indicate that concanavalin A binds to the CD11c molecule and this binding is responsible for the concanavalin A-induced respiratory burst in PMA-differentiated U937 cells as well as in human mature monocytes and neutrophils.

Antibodies, Monoclonal↗
PubMed1990

The induction of vimentin gene expression by sodium butyrate in human promonocytic leukemia U937 cells.

The administration of 1 mM sodium butyrate induced the phenotypic differentiation of human promonocytic leukemia U937 cells, as judged by the expression of cD11b and cD11c antigens, two differentiation-specific surface markers. At the same time, butyrate greatly induced the expression at the mRNA level of the vimentin gene. The increase in the level of this RNA started at 6 h of treatment and reached the maximum at Hour 24. Such an increase was caused at least in part by a stimulation in the rate of gene transcription, as suggested by transcription assays in isolated nuclei. Experiments in the presence of cycloheximide suggested that vimentin induction is probably a direct response to the action of butyrate, not mediated by the prior induction of other gene products. Unlike the case of vimentin, the levels of other RNAs, namely beta-actin, ornithine decarboxylase, and c-myc, were not enhanced, but they decreased at different times of treatment with butyrate. Finally, we observed that butyrate induced also the differentiation of HL60 cells, another human myeloid cell type. Nevertheless, the drug failed to stimulate the expression of vimentin in this cell line.

Butyrates↗
PubMed1989

S-phase inhibitors induce vimentin expression in human promonocytic U-937 cells.

The administration of hydroxyurea (3 x 10(-4) M) and cytosine arabinoside (10(-7) M) greatly induces the expression of the vimentin gene in human promonocytic leukemia U-937 cells. The induction takes place at both the mRNA and protein levels, as demonstrated by Northern blot, immunoblot and immunofluorescence assays. On the contrary, the drugs inhibit the expression of c-myc and ornithine decarboxylase, and do not modify significantly the expression of beta-actin. Since hydroxyurea and cytosine arabinoside trigger the phenotypic differentiation of U-937 cells, as demonstrated by the induction of the differentiation-specific CD11b and CD11c antigens, it is concluded that vimentin expression might be implicated in the maturation of these cells.

Antigens, Differentiation, Myelomonocytic↗
PubMed1989

Characterization of a novel myeloid antigen regulated during differentiation of monocytic cells.

The monoclonal antibody HC1/6 generated against phorbol 12-myristate 13-acetate-treated U-937 cells recognizes a new cell surface antigen with a broad relative molecular mass ranging from 100 to 150 kDa. This antigen is also present on monocytes, platelets and endothelial cells and is weakly expressed by granulocytes. In contrast, it is absent from T, B and erythroblastoid cells. The antigen HC1/6 is also expressed by normal tissue macrophages in tonsil, lung and kidney, as well as in skin biopsies from pathologies such as sarcoidosis and lepromatous leprosy. The expression of the HC1/6 antigen is increased up to 5-fold when U-937 (promonocytic) and HL-60 (myelomonocytic) cell lines are stimulated with phorbol 12-myristate 13-acetate. Conversely, the expression of the HC1/6 antigen is down-regulated in monocytes upon treatment with interferon-gamma. These findings are discussed in relation with other myeloid cell surface markers.

Antibodies, Monoclonal↗
PubMed1989

A monoclonal antibody to CD11c antigen inhibits the production of superoxide anion induced by concanavalin A in PMA-differentiated U-937 cells.

We have examined the effect of different monoclonal antibodies (MAb) to the CD11/CD18 family of surface antigens on the production of superoxide anion by phorbol myristate acetate (PMA)-differentiated U-937 cells upon stimulation with concanavalin A (Con A). The anti-CD11c MAb HC1/1 displayed a significant inhibition, whereas MAb to the other members of the CD11 family did not show a relevant inhibitory effect. These findings suggest that the CD11c antigen is involved in the triggering of the respiratory burst response by mononuclear phagocytic cells.

Antibodies, Monoclonal↗
PubMed1989

Poliovirus infection interferes with the phorbol ester-induced differentiation of the monocytic U937 cell line.

Monocytic U937 cells can differentiate in vitro into macrophage-like cells by treatment with phorbol esters such as phorbol 12-myristate 13-acetate (PMA). We have analyzed the effect of poliovirus infection in this pathway of differentiation. Poliovirus RNA replication took place in both untreated and PMA-treated U937 cells infected before or after PMA addition, although a slight reduction in poliovirus RNA levels was observed in PMA-treated cells at late times postinfection. Total protein synthesis remained unchanged during the first 5 h of infection both in normal and PMA-treated cells. However, an inhibition on total RNA synthesis was observed early in infection. PMA-induced c-myc mRNA expression was abolished when infection took place 1 h before PMA addition but was just partially inhibited when poliovirus was added 1 h after PMA stimulation. Fluorescence flow cytometry analysis revealed that poliovirus infection induced an increase in the number of 4F2 molecules per cell in normal U937 cells and a slight decrease in the number of positive cells for the antigens CD14, CD4 and CD11c in both untreated or PMA-treated U937 cells. These findings suggest that poliovirus infection of U937 cells interferes at various levels with monocyte maturation yielding cells which are unable to undergo the complete pathway of differentiation to macrophages.

Antigens, Surface↗
PubMed1988

Intracellular localization of a leukocyte adhesion glycoprotein family in the tertiary granules of human neutrophils.

Stimulation of human neutrophils by the chemoattractant formyl-methionyl-leucyl-phenylalanine or the calcium ionophore A23187 induced increments in the cell surface expression of the alpha subunits of Mo1 (CD11b) and gp150, 95 (CD11c) and their common beta subunit (CD18). These increases showed a good correlation with the extracellular release of gelatinase, a marker for tertiary granules in human neutrophils. Conversely, the cell surface expression of the alpha subunit of the lymphocyte function-associated antigen-1 or LFA-1 (CD11a) was not altered upon cell activation. By subcellular fractionation and immunoprecipitation studies, we have found that CD11b, CD11c and CD18 molecules were mainly localized in the membranes of tertiary granules, which were resolved from the specific and azurophilic granules as well as from the plasma membrane fraction.

Antigens, Surface↗
PubMed1988

Characterization of a CD11c-reactive monoclonal antibody (HC1/1) obtained by immunizing with phorbol ester differentiated U937 cells.

A mouse monoclonal antibody (HC1/1) specific for a differentiation marker of human monocytes and granulocytes has been generated by using as immunogen the monocytic cell line U937 differentiated with phorbol esters. This differentiation antigen has been characterized as the p150/95 member of the CD11 family of glycoproteins by cellular distribution studies, immunoprecipitation and competition experiments with MAb 3.9 specific for the CD11c antigen. Immuno-alkaline phosphatase staining of normal tissue sections with the HC1/1 MAb demonstrated that the CD11c antigen is a useful macrophage marker. Furthermore, the MAb HC1/1 stains specifically populations of macrophages on skin and lymph node sections from different pathologies such as Sarcoidosis, Granuloma annulare, Lepromatous leprosy and Toxoplasmosis.

Antibodies, Monoclonal↗