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R Vilella

Publications and source records attributed to R Vilella.

11 recordsLinked to original sources
PubMed1992

Activation of human phagocytes through carbohydrate antigens (CD15, sialyl-CD15, CDw17, and CDw65).

The leukocyte carbohydrate (CHO) Ag CD15, sialyl-CD15, and CDw65 have recently been found to function as ligands for CD62 and ELAM-1 cell adhesion molecules on platelets and endothelium, respectively. Cell adhesion ligands also may act as receptors capable of signal transduction. We therefore investigated the possibility that these CHO Ag and CDw17, a glycolipid Ag whose expression is regulated by leukocyte activation, may have receptor-like characteristics. The effects of antibody cross-linking of CHO Ag on phagocyte activation were measured by using flow cytometry and fluorescent indicators for cytoplasmic calcium ions, oxidative burst, and the granule-associated proteins CD11b and CD67. Cross-linking of CD15, sialyl-CD15, CDw65, or CDw17 induced a moderate release of calcium ions into the cytoplasm of granulocytes, a strong activation of oxidative burst, and a low up-regulation of CD11b and CD67 compared to the effects of treatment with 4 microM FMLP. The results suggest a role for CHO Ag in leukocyte signal transduction and support the view that these molecules are involved in phagocyte activation.

Antibodies, Monoclonal↗
PubMed1991

Induction of interleukin 2 (IL 2) and interferon-gamma and enhancement of IL 2 receptor expression by a CD26 monoclonal antibody.

The ability of the 134-2C2 monoclonal antibody (mAb; CD26) to transmit an activation signal and to affect T cell proliferation has been studied. The 134-2C2 mAb, although not being mitogenic by itself, is able to increase the proliferation of purified T cells in the presence of exogenous interleukin 2 (IL2) or phorbol 12-myristate 13-acetate (PMA). No effect of our mAb was observed on the proliferation of T cells induced by other stimuli such as Sepharose-bound CD3 mAb, phytohemagglutinin or calcium ionophore. Since the co-stimulatory effect of 134-2C2 mAb on PMA-induced T cell proliferation was strongly inhibited by an anti-Tac antibody, its involvement on the IL2/IL2 receptor pathway was investigated. An increased IL2 secretion in T cells cultured with PMA plus 134-2C2 mAb was observed and Northern blot analysis showed that the mAb 134-2C2 acts synergistically with PMA favoring the induction of both IL2 and interferon-gamma mRNA synthesis, as well as the enhancement of IL2 receptor and transferrin receptor mRNA expression. Studies on mechanisms implicated in signal transduction showed that 134-2C2 mAb modifies neither intracellular calcium levels nor phosphoinositide breakdown. Additionally, no effect was exerted on protein kinase C translocation. These data suggest that the CD26 antigen is involved in T cell activation in an IL2/IL2 receptor-dependent pathway.

Antibodies, Monoclonal↗
PubMed1990

CD27 induction on thymocytes.

CD27 mAb recognize a disulfide-linked homodimer of 55 kDa present in the majority of T cells and in a minor subpopulation of thymocytes. Although an increase of CD27 expression has been described in activated T cells, this Ag is poorly expressed in long term growing T cells. It has been also reported that CD27- becomes CD27+ upon activation. In the aim to better know the relationship between CD27 expression and the activation and maturation processes, the induction of this Ag in thymocytes was analyzed. The results obtained in this work show that: 1) CD27 is expressed only in thymocytes with high CD3 Ag density. 2) Its expression can be induced in low density CD3 CD4+ CD8+ cells by Con A and in low CD3 Ag density by PMA+ionomycin. 3) PMA alone or in combination with rIL-2 induces CD25 and CD71 expression but not CD27. 4) Unlike CD27, the Ag CD45RA, CD26, and CD76, which are present only in a minor thymocyte subpopulation, are not induced in double positive thymocytes. Because it has been reported that cyclosporin A interferes with thymocytes maturation and blocks the transition from double to single positive cells, its effect was measured on CD27 induction. Cyclosporin A did not inhibit CD25 expression induced by both Con A and PMA+ionomycin, but under these conditions it inhibited the induction of CD27. In this paper we discuss whether CD27 could be implicated in T cell maturation.

Antibodies, Monoclonal↗
PubMed1990

Monoclonal antibodies against the human lymphocyte differentiation antigen CD 76 bind to gangliosides.

Two monoclonal antibodies, HD 66 and CRIS-4, by which the new CD 76 B-cell-associated cluster was defined, bound to several gangliosides (sialic acid containing glycolipids) of different polarity. One of the gangliosides recognized by HD 66 could be identified as NeuAc alpha 2-6Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc-beta 1-1'Cer. This antigen was enzymatically synthesized. Sialidase treatment of the ganglioside antigens abolished binding of HD 66 and CRIS-4.

Antibodies, Monoclonal↗
PubMed1990

Differential effects of anti-CD45 monoclonal antibody on human B cell proliferation: a monoclonal antibody recognizing a neuraminidase-sensitive epitope of the T200 molecule enhances anti-immunoglobulin-induced proliferation.

We have generated seven monoclonal antibodies (mAb) that recognize the T200 molecule. These mAb have been classified by competitive binding assay in flow cytometry into three groups each reacting with a different epitope of the T200 molecule: (a) 136-4B5, that shows a sialic acid nature, (b) 135-4H9, 135-4C5, 144-2, 155-2 and (c) 72-5D3, 124-2H12b. A heterogeneous effect was observed when they were tested on an anti-immunoglobulin-induced B cell proliferation. Whereas 72-5D3 and 135-4H9 mAb inhibited the proliferative response of B cells, 136-4B5 mAb greatly enhanced it, both effects being dose dependent. We can conclude that anti-CD45 mAb have a different and contrary functional behavior on anti-Ig-induced B cell proliferation, depending on the epitope recognized. The basis for such a difference could reside in the glucidic nature of the epitope recognized by the 136-4B5 mAb.

Antibodies, Anti-Idiotypic↗
PubMed1990

Immunophenotype of blast cells in acute myelofibrosis.

The immunophenotype of peripheral blood blast cells from six patients with acute myelofibrosis was studied using a panel of monoclonal antibodies directed against granulocytic, erythroid, megakaryocytic and lymphoid antigenic determinants. In all patients most of the blast cells were labeled with anti-HLA-DR and with the early myelomonocytic antibodies My7 (CD13), My9 (CD33) and B1-3C5 (CD34) (3/3). In three cases, platelet antibodies Edu3 (CD41) and GPIIIa (CD61) reacted with about 30% of blast cells. TdT was positive in two out of six samples studied. Lymphoid markers T3 (CD3), Leu9 (CD7), J5 (CD10), B4 (CD19) and B1 (CD20) were negative in all cases. These results suggest that blast cells are mainly of immature myelocytic origin. However, the coexistence of megakaryoblasts cannot be ruled out in the cases with a proportion of cells that are positive with Edu3 and GPIIIa antibodies.

Acute Disease↗
PubMed1990

Involvement of the CDw50 molecule in allorecognition.

The CDw50 differentiation antigen is defined by 101-1D2 and 140-11 monoclonal antibodies (mAb), both produced and characterized in our laboratory. This molecule is broadly expressed on hematopoetic cells but not on other cells. In this report we show that these 2 mAb recognize different epitopes of the same molecule, which are resistant to neuraminidase and proteases. We also demonstrate that the CDw50 antigen is expressed on thymocytes and T lymphocytes as an N-glycosylated glycoprotein monomer with a relative molecular weight (Mr) of 130,000 daltons with intrachain disulfide bonds, and that this molecule is resistant to treatment with phosphatidylinositol (PI) phospholipase C and therefore probably not PI-anchored to the membrane. CDw50 is a poorly or non-constitutively phosphorylated molecule that becomes phosphorylated by treatment with phorbol 12-myristate 13-acetate (PMA) of peripheral blood mononuclear cells (PBMC). The addition of affinity-purified CDw50 mAb inhibits primary mixed lymphocyte culture (MLC) but not secondary MLC, cytotoxicity or proliferation induced by mitogens. The inhibition of alloreactivity is mediated at the level of both responding and stimulator cells.

Antibodies, Monoclonal↗
PubMed1987

A second signal for T cell mitogenesis provided by monoclonal antibodies CD45 (T200).

The induction of T cell mitogenesis through CD3 is a complex process that requires at least two signals. The first one can be provided by Sepharose-bound CD3. The second one is normally provided by monocytes. The signal provided by Sepharose-bound CD3 is unable by itself to induce mitogenesis in monocyte highly depleted cells (MHDC). We describe here that the monoclonal antibody (mAb) 72-5D3 belonging to CD45 (T200), which was not mitogenic by itself, could replace monocytes when MHDC were activated by Sepharose-bound CD3. That is to say, in the absence of monocytes, mAb 72-5D3 gave a second signal necessary for T cell proliferation. Using eleven anti-CD45 mAb from other investigators we show that this effect is not a peculiar characteristic of 72-5D3 mAb. The effect of the mAb 72-5D3 was only effective in CD4-positive cells and was not observed when MHDC were activated with either soluble CD3 or concanavalin A. As both phorbol myristate acetate and mAb 72-5D3 can replace monocytes, a comparative study of their effects was undertaken. Phorbol myristate acetate but not mAb 72-5D3 induced proliferation of MHDC when recombinant interleukin 2 (rIL2) was added. On the other hand mAb 72-5D3 induced IL2 production in MHDC activated by Sepharose-bound CD3 and increased the IL2 production in Sepharose-bound CD3-activated peripheral blood mononuclear cells. In conclusion, data presented in this report indicate that the T200 molecule could be involved in T cell proliferation by giving a signal that induces the production of IL2 and bypasses the necessity of monocytes.

Animals↗