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Biomedical subjects

R Palacios

Publications and source records attributed to R Palacios.

At least 145 records · Page 8Linked to original sources
PubMed1984

Distinct mechanisms may account for the growth-promoting activity of interleukin 3 on cells of lymphoid and myeloid origin.

We have investigated whether interleukin 3 (IL-3) supports the growth of cells of different lineages by the same mechanism(s). The experiments were carried out with Ea3 cells, a mouse pre-B cell line, and S-480-3 cells, a mouse basophil cell line, both of which are totally IL-3 dependent. We found that Ea3 lymphocytes but not S-480-3 basophils absorb partially purified IL-3. Both Ea3 and S-480-3 cells respond to IL-3 by increasing anaerobic glycolysis as determined by lactic acid production. S-480-3 cells responded to exogenous ATP by maintaining proliferation and reducing lactic acid production, but Ea3 lymphocytes are refractory to exogenous ATP. We conclude that there may be two distinct mechanisms by which cells respond to IL-3, indicated by early events concerning the binding of IL-3 and the effect of exogenous ATP on respiratory metabolism. One appears to be a ligand-receptor-mediated mechanism in lymphoid cells and the other to be a mechanism that is partially replaceable by exogenous ATP in nonlymphoid cells not associated with lymphoid-like receptors. Our findings may explain (i) the apparent variety of cell lineages promoted by IL-3 by a widely available mechanism that supports glycolysis and, therefore, enables both proliferation and possibly expression of binding sites for lineage specific differentiation factors and (ii) the existence of lymphocytes that express receptors specific for IL-3 and are inducible for other characteristics and functions in a regulated manner.

Animals↗
PubMed1984

Immunologic evaluation of T chronic lymphocyte leukaemia cells in a patient with a concomitant IgA2 myeloma.

Peripheral blood lymphocytes from a patient with OKT3, OKT4, OKT17 positive T CLL and a concomitant IgA2/lambda myeloma were found to be suppressive in cocultivation experiments and after in vitro preactivation . Although chromosomal analysis after stimulation with T or B cell mitogens suggested a common origin of the two malignancies, T cells did not carry structures recognized by an anti-idiotypic antiserum raised against the purified M-component. Only Fc mu receptors were found on the T cells with conventional rosetting assays, although a weak binding of Latex particles coated with the purified IgA M-component could occasionally be recorded. When purified T cells were submitted to FACS-analysis after incubation with the FITC-conjugated purified M-component, two subsets could easily be distinguished in normal T cells, whereas only the high affinity-binding subset could be found in the patient.

Aged↗
PubMed1984

Production of lymphokines by circulating human T lymphocytes that express or lack receptors for interleukin 2.

The capacity for circulating human T cells which have or lack receptors for interleukin 2 (IL 2) to produce IL 2, interleukin 3 (IL 3), and interferon-gamma (IFN-gamma) under the stimulus of phytohemagglutinin was studied. By using the monoclonal anti-Tac antibody which reacts against IL 2 receptors on human T cells, concanavalin A-treated T cells were separated into IL 2 receptor-positive (Tac+ T cells) and IL 2 receptor-negative (Tac- T cells) lymphocytes. The results show that Tac+ T cells secreted IL 2 and IFN-gamma but not IL 3. Tac- T cells produced IL 2 and IL 3 but not IFN-gamma. It is concluded that: 1) both T cells lacking and T cells having receptors for IL 2 produce IL 2, but only IL 2 receptor-negative T cells appear to secrete IL 3; and 2) virtually all of the T cells that produce IFN-gamma after PHA stimulation express receptors for IL 2.

Antibodies, Monoclonal↗
PubMed1983

Production of human immune interferon (Hu IFN-gamma) studied at the single cell level. Origin, evidence for spontaneous secretion and effect of cyclosporin A.

A reverse hemolytic plaque assay has been developed which specifically detects secretion of human immune interferon (Hu IFN-gamma) at the single cell level. Unstimulated peripheral blood lymphocytes from healthy adult volunteers spontaneously secreted IFN-gamma. Stimulation of these cells with concanavalin A, phytohemagglutinin, or the UCHT1 monoclonal anti-human T cell antibody significantly increased the number of IFN-gamma-secreting cells. The cell producing IFN-gamma, both spontaneously and after UCHT1 antibody stimulation, is an OKT3+,4+,8-,HLA-DR-T lymphocyte as determined at the single cell level. Finally, cyclosporin A, a potent and selective immunosuppressive drug for T cells, strongly inhibited the secretion of IFN-gamma as assayed at the cell level. This IFN-gamma reverse hemolytic plaque assay has great potential for the further study of IFN-gamma both in physiological and pathological conditions.

Antibodies, Monoclonal↗
PubMed1983

Monoclonal antibodies against HLA-DR antigens replace T helper cells in activation of B lymphocytes.

In the presence but not in the absence of pokeweed mitogen (PWM), monoclonal antibodies against HLA-DR antigens 147 and 164 helped highly purified B lymphocytes to proliferate and mature to Ig-secreting cells. In contrast, neither anti-DR antibody 231 nor the UCHT1 monoclonal anti-human T cell antibody (both of the same isotype as the 147 and 164 anti-DR antibodies) exhibited any helper activity on B cells. B cells pulsed with PWM and subsequently cultured in the presence of anti-DR antibody 147 or 164 proliferated and secreted Ig, whereas B cells that first were pulsed with antibody 147 or 164 and then incubated with PWM did not. PWM alone did not induce any of these responses on purified B cells. Also, antibodies 147 and 164 significantly increased the number of Ig-secreting cells obtained from the WT51 Epstein-Barr virus-transformed B-cell line. Anti-DR antibody 231 inhibited the helper activity on WT51 cells mediated by anti-DR antibody 164. Finally, anti-DR antibodies 147 and 164 assisted B cells from the spleen of athymic nu/nu mice (which bear I-E-encoded products) to produce IgM antibodies against sheep erythrocytes. However, these antibodies had no effect on mouse B cells which do not express on their surface I-E-encoded Ia antigens. Taken collectively, these findings suggest that the structures detected by anti-DR antibodies 147 and 164 on B lymphocytes function as acceptors/transducers of T-cell-derived helper signals.

Animals↗
PubMed1983

Nitrogen source regulates glutamate dehydrogenase NADP synthesis in Neurospora crassa.

Neurospora crassa glutamate dehydrogenase-NADP (EC 1.3.1.3) has a higher activity when mycelium is grown on ammonium or nitrate as nitrogen source than when grown on glutamate or glutamine. Quantitative immunoelectrophoresis established that, under all conditions, enzyme activity corresponded to enzyme concentration. Isotope incorporation studies demonstrated that the nitrogen source exerts its regulation at the level of de novo enzyme synthesis.

Glutamate Dehydrogenase↗
PubMed1983

Genetic and biochemical characterization of glutamine synthetase from Neurospora crassa glutamine auxotrophs and their revertants.

In this paper we present the isolation and characterization of glutamine auxotrophs of Neurospora crassa and their revertants. The results show that although various enrichment procedures were used, we found only two types of auxotrophs. Genetic crosses performed between the different mutants showed that the mutations responsible for their phenotypes were highly linked and probably affected the same gene. The biochemical characterization of the glutamine synthetase polypeptides of the different mutants showed that both types contained the alpha monomer. However, in place of the normal beta monomer, each type had a new polypeptide differing from normal beta either in its molecular weight or in its isoelectric point. On the other hand, the revertants had only the alpha monomer and were capable of growing without glutamine. On the basis of these data, we propose that the lack of glutamine synthetase activity in the auxotrophs is due to the interaction of the altered beta with the alpha monomer, and as a consequence the alpha monomer of the revertants regains its activity because of the absence of the altered beta.

Centrifugation, Density Gradient↗
PubMed1982

Development and continuous growth in culture of interleukin 2-producer lymphocytes from athymic nu/nu mice.

Splenocytes of nu/nu mice treated with serum thymic factor (FTS) for 3 or more days followed by stimulation with either phorbol myristate acetate (PMA) or concanavalin A (Con A) produced interleukin 2 (IL 2) as determined in two indicator systems, namely, support of growth of IL 2-dependent T cells and promotion of Con A-initiated mitogenesis of thymocytes. However, neither mitogens nor FTS alone could induce nude mice cells to product IL 2. Supernatants derived from the tumor cell line WEHI-3 (WEHI-3 conditioned media) induced and supported continuous growth in culture of Thy-1.2+, Lyt-1+2- lymphocytes from athymic nude mice capable of producing IL 2 after their stimulation by either PMA or Con A. The growth of these IL 2-producer cell lines strickly depends on the presence of WEHI-3 conditioned media, as in the absence of it they die 24-48 h later. In addition, WEHI-3 conditioned media have been supporting the growth of IL 2-producer cell lines derived from nude mice for 3 1/2 months. The helper factor contained in WEHI-3 conditioned media responsible for the above biological activity has an apparent mol. wt. of approximately 40 000 as determined by Sephadex G-100 chromatography and lacks IL 1 and IL 2 activities, but efficiently supports the growth of IL 2-producer cells derived from nude mice and the peripheral blood of normal human volunteers. These results indicate that the helper factor in WEHI-3 conditioned media which enables the generation and continuous proliferation in culture of IL 2-producer cells in nude mice is distinct from interleukin 1, IL 2 and FTS (mol. wt. 864). Finally, the possibly functional relationship of FTS and the helper factor produced by WEHI-3 cells is discussed.

Animals↗
PubMed1982

Accessory function of human tumor cell lines. I. Production of interleukin 1 by the human histiocytic lymphoma cell line U-937.

The established human histiocytic lymphoma cell line U-937 spontaneously produced a factor with biological activity similar to that ascribed to interleukin 1 (IL 1). Actually, supernatants from U-937 cells promoted proliferation of thymocytes initiated by concanavalin A (Con A) and replaced the requirement of accessory cells for activation of highly purified circulating T lymphocytes induced by Con A. Phorbol myristate acetate (PMA) significantly increased the titers of the helper factor produced by U-937 cells as compared to that secreted by non-PMA-treated U-937 cells or PMA-stimulated P388D1 murine macrophage tumor cells. Generally U-937 cells did not secrete detectable IL 1 activity during the first 24-48 h of culture. However, after this initial period the level of IL 1 activity increased and reached a maximum at 5-6 days of culture. Finally, the helper factor released by U-937 cells had an apparent mol. wt. of 12000-15000 as determined by Sephadex G-100 chromatography and lacked interleukin 2 activity as shown by its inability to support growth of IL 2-addicted T cell lines. To our knowledge this is the first report of an established human cell line capable of producing IL 1.

Animals↗
PubMed1982

Epstein-Barr virus increases the proliferative response and the generation of suppressor and cytotoxic T-cell functions in autologous mixed lymphocyte reaction.

Epstein-Barr virus (EBV) infection of stimulator cells significantly increased the proliferative response of T cells in the autologous mixed lymphocyte reaction (AMLR). The addition of a monoclonal anti-HLA-DR antibody to AMLR cultures in which either EBV-infected or non-infected non-T cells were used as stimulator cells strongly inhibited the proliferative response irrespective of the presence of EBV. It is concluded that EBV does not by itself activate the responding cells and that HLA-DR antigens are necessary to trigger T cells. Increased generation of suppressor T cells, determined in both alloantigen-induced DNA synthesis and pokeweed-mitogen-stimulated immunoglobulin production, was found after an EBV infection of stimulator cells. Similarly, EBV-infected non-T cells significantly increased the generation of killer T cells, determined in three different types of target cells: phytohaemagglutinin-stimulated mononuclear cells, EBV-transformed cells, and concanavalin-A-activated murine spleen cells. The increased T-cell responses after an EBV infection may reflect the attempts in vivo to control and hold in check the viral infection.

Antibodies, Monoclonal↗
PubMed1982

Hydrocortisone abrogates proliferation of T cells in autologous mixed lymphocyte reaction by rendering the interleukin-2 Producer T cells unresponsive to interleukin-1 and unable to synthesize the T-cell growth factor.

Hydrocortisone (HC-A) inhibited the proliferative response in the autologous mixed lymphocyte reaction (AMLR). The inhibitory activity became apparent 48 h after initiation of the cultures and was maintained throughout the culture period. T cells from cultures treated with HC-A showed a proliferative response to interleukin-2 (IL-2) of a similar degree as T cells from cultures not exposed to this drug. Hydrocortisone abrogated the production of IL-2 in AMLR. The addition of interleukin-1 (IL-1) to HC-A-treated cultures did not restore or increase the synthesis of IL-2, whereas IL-1 added to non HC-A treated cultures significantly enhanced the synthesis of IL-2, Finally, IL-2 but not IL-1 could overcome the abrogatory effect of hydrocortisone on proliferation of T cells induced by AMLR. These results indicate that HC-A inhibits proliferation of T cells in AMLR by causing the IL-2 producer T cells to become unresponsive to IL-1 and unable to synthesize IL-2. This drug does not, however, interfere with the process by which resting T cells acquire responsiveness to IL-2.

Humans↗
PubMed1982

Interleukin-2 and serum thymic factor enable autologous rosette-forming T lymphocytes to generate helper and cytotoxic functions.

The autologous rosette-forming T cells (Tar cells) isolated by means of their ability to form rosettes with autologous erythrocytes were characterized by the use of OKT monoclonal anti-human T-cell subset antibodies and a monoclonal anti-HLA-DR antibody. We found that the phenotype of Tar cells was OKT 3+4+8+Dr- as determined by both indirect immunofluorescence microscopy and complement-mediated killing of 51Cr-labelled Tar cells. In addition, we found that Tar lymphocytes were able to develop cytotoxicity against allogeneic and trinitrophenol (TNP)-conjugated autologous target cells in the presence of interleukin-2 (IL-2) or serum thymic factor. However, these cells showed little or nor cytotoxicity in the absence of interleukin-2 or serum thymic factor. Tar lymphocytes generated helper function for B lymphocytes in the presence of interleukin-2 in both pokeweed mitogen (PWM)- and purified protein derivative (PPD)-stimulated cultures. Nevertheless, non-IL-2-treated Tar cells did not exhibit any helper activity on B cells. Finally, pretreatment of Tar cells with 1000-1500 rad of X ray made these cells unable to develop helper function for B lymphocytes. It is concluded that: (1) OKT 3+4+8+Dr- Tar cells are able to generate cytotoxicity against alloantigens and TNP-labelled self structures provided they are stimulated by IL-2 or serum thymic factor; (2) these cells need both to proliferate and to receive help from IL-2 to develop helper cells capable of assisting B-lymphocyte differentiation into plasma cells in both PWM- and PPD-stimulated cultures.

Antibodies, Monoclonal↗
PubMed1982

Cyclosporin A inhibits thymus-dependent but not thymus-independent immune responses induced by dextran B512.

We have compared previous studies of the immune response to dextran (Dx) B512 in thymus-deficient nu/nu and thymectomized, lethally irradiated, and bone marrow-reconstituted mice with those obtained with cyclosporin A (CyA) as a T-cell-inhibiting drug. Our data show that only immune responses to TD forms of Dx B512 are susceptible to suppression by CyA, whereas anti-alpha 1-6 and anti-DNP antibodies induced by high molecular weight dextran and DNP-native Dx, respectively, were not inhibited. Similar results were obtained when polyclonal responses were studied. The polyclonal response induced by another dextran preparation, the polyanion dextran sulphate (DxS), was inhibited by CyA to the same extent as polyclonal T-cell activation by T-cell mitogens.

Animals↗