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Biomedical subjects

N Gualde

Publications and source records attributed to N Gualde.

At least 55 records · Page 3Linked to original sources
PubMed1989

Effect of arachidonic acid metabolites on CR1 expression by B-lymphocytes.

The effect of arachidonic acid metabolites on the expression of the receptor for the C3b/C4b fragment of complement (CR1) by human B-lymphocytes was investigated. Kinetic experiments to determine CR1 expression over time indicated that the maximal receptor number occurred at 2 h, followed by a return to baseline values. Addition of 10(-4) M puromycin to the cells suggested that the increase was due to the expression of an intracellular pool and not de novo synthesis of new receptor molecules. B-lymphocytes were incubated with arachidonic acid, 15-hydroxyeicosatetraenoic acid, leukotrienes B4 or C4 or prostaglandin E2 (PGE2). The quantity of membrane antigenic binding sites was determined before and after incubation. The lipoxygenase metabolites did not alter CR1 numbers. In contrast, PGE2 significantly decreased (P less than 0.05) the quantity of CR1 expressed. In kinetic experiments, PGE2 blocked the maximal expression of CR1 seen at 2 h, indicating that it prevents the appearance of an intracellular pool of receptor. These results show that CR1 number on B-lymphocytes can be altered by at least one arachidonic acid metabolite. This may offer a partial explanation for the inhibitory effects of PGE2 on B-cell proliferation and immunoglobulin secretion since CR1 is implicated in B-lymphocyte differentiation and specific antibody response.

Arachidonic Acids↗
PubMed1989

A simple in vitro test to evaluate biocompatibility of dialysis membranes.

As arachidonic acid metabolites are implicated in hypersensitivity reactions, we measured arachidonic acid metabolites of dialysed patient's granulocytes, preincubated with different dialysis membranes. Results indicate that cuprophan and cellulose acetate membranes partially inhibit in vitro production of 15-HETE and 5-HETE, whereas polyacrylonitrile membrane does not. This suggests that polyacrylonitrile is a more biocompatible membrane.

Acrylic Resins↗
PubMed1988

Effect of PGE2 and LTB4 on vicia villosa binding lymphocytes.

Since there is a good deal of evidence that vicia villosa lectin (VVA) binds to contrasuppressor cells, mouse splenocytes and thymocytes were sorted by binding to VVA-coated Petri dishes. It was observed that vicia villosa adherent cells (VVA(+)) did not proliferate when mitogens were added to cultures, but they did enhance the thymidine uptake of PHA or ConA stimulated vicia villosa non-adherent (VVA(-)) splenocytes. PGE2 treatment of VVA(+) splenocytes or VVA(+) immature thymocytes did not very much affect the VVA(+) cell behavior. On the other hand, LTB4 increased the enhancing capability of VVA(+) splenocytes. Therefore, investigations dealing with the effects of LTB4 on lymphocyte subsets which may include VVA(+) cells should take into consideration the possible presence of contrasuppressor cells.

Animals↗
PubMed1987

Alterations in the human immune response to the hepatitis B vaccine among the elderly.

The specific binding of hepatitis B (HBs) antigen by lymphocytes from old people immunized with hepatitis B vaccine was explored. For that purpose HBs antigen was combined with fluorescent microspheres, and labeled antigen was allowed to react with lymphocytes from HBs vaccine-responsive or unresponsive people. Lymphocytes from 10 responders and 14 nonresponders were tested for their antigen-binding ability. For controls, lymphocytes were incubated with microspheres bearing human albumin. Lymphocytes from 8 out of 10 responders were able to recognize HBs antigen; for the nonresponders the ratio was 9 out of 14. HBs-binding lymphocytes were B cells but not T lymphocytes. B and T cells from responders and nonresponders were combined and cultivated for 8 days in the presence of HBs antigen, and antibody-producing cells were counted. Neither B cells alone nor B cells plus T cells from nonresponders were able to produce antibody. On the other hand B cells from unresponsive old people produced antibodies when they were cultivated in the presence of HBs antigen and T cells from responsive old people. These data suggest that some elderly individuals who do not produce antibody after in vivo immunization by HBs vaccine do have antibody-producing cells. Instead of a gap in their immune repertoire, these people are suffering from immune dysfunction.

Aged↗
PubMed1986

Cyclooxygenase and lipoxygenase-like activity in Drosophila melanogaster.

To determine the possible activity of cyclooxygenase and lipoxygenase like enzymes in Drosophila melanogaster, we have investigated whether fly homogenates can biosynthesize prostaglandins and HETEs. Incubation of fly extracts with AA yields a mixture of 15- 12- 9- and 8-HETE as detected by selected ion monitoring GC-MS. Also the combination of HPLC-RIA using a PGE antibody shows the presence of endogenous PGE2 immunoreactivity in the extracts (405 pg/g in males and 165 pg/g in females). We have also detected the presence of lipoxygenase like immunoreactivity in the reproductive male system by using immunocytochemical techniques in whole body sections of the fly as well as reactivity in the digestive system of both males and females. Finally, we have not been able to detect endogenous AA in the fly by GC-MS methods. However, estimates by GC-MS of the total body fatty acids indicate substantial amounts of potential AA precursors.

Animals↗
PubMed1986

15-HETE "modulates" expression of C3b receptor (CR1) antigen on peripheral blood B-lymphocytes.

We have studied the effect of the lipoxygenase metabolite, 15-HETE, on the expression of the human C3b receptor (CR1) by a B-lymphocyte enriched population of human peripheral blood leukocytes. The number of CR1 antigenic sites expressed by B-lymphocytes isolated from HLA typed donors was determined by equilibrium binding studies using an 125 I-labelled mouse monoclonal anti CR1 antibody before and after 16 hrs incubation in RPMI alone or containing 10(-6)M, 10(-7)M or 10(-8)M final concentration of 15-HETE. In B44- subjects CR1 expression on B cells increased 63% after incubation in RPMI alone. This increase was inhibited in the presence of 10(-6)M and 10(-7)M 15-HETE (23% and 30% increase respectively). In contrast, B44+ individuals showed a smaller increase in CR1 numbers when incubated in RPMI alone. In the presence of 15-HETE CR1 antigenic sites continued to increase. When B44+ subjects were classified as A29+ or A29-, donors that were A29+ B44+ accounted for the augmentation observed while A29- B44+ individuals did not differ from individuals that were A29- B44-.

Antigens, Surface↗
PubMed1985

Induction of suppressor cells from peripheral blood T cells by 15-hydroperoxyeicosatetraenoic acid (15-HPETE).

15-hydroperoxyeicosetetraenoic acid (15-HPETE), a lipoxygenase metabolite of arachidonic acid, inhibited polyclonal IgG and IgM production in pokeweed mitogen (PWM)-stimulated cultures of human peripheral blood mononuclear cells, whereas 15-hydroxyeicosetetraenoic acid (15-HETE) had little effect in this system. T cells preincubated for 18 hr with 15-HPETE caused substantial inhibition of IgG and IgM production of fresh, autologous B and T cells stimulated by PWM. The suppressive effect of the 15-HPETE-treated cells was lost if the cells were irradiated before the PWM culture, but not by treatment with mitomycin C. The suppressive effect was also lost if OKT8+ T cells were removed after, but not before, preincubation of the T cells with 15-HPETE. OKT8- T cells incubated with 15-HPETE for 18 hr showed a large increase in the percentage of cells staining with directly fluoresceinated Leu-2, another marker for suppressor cells. Thus, 15-HPETE induces functional and phenotypic suppressor cells from resting human peripheral blood T cells.

Adult↗
PubMed1985

Effect of lipoxygenase metabolites of arachidonic acid on proliferation of human T cells and T cell subsets.

The lipoxygenase products LTB4 and 15 HPETE have been reported to stimulate T suppressor cell function and also to inhibit [3H]thymidine incorporation into mitogen-stimulated T cells. This present report documents that although these compounds do indeed inhibit [3H]thymidine incorporation into unfractionated T cells, they significantly enhance [3H]thymidine incorporation into T cell preparation enriched for cells bearing the cytotoxic suppressor cell phenotype identified by the OKT8 monoclonal antibody. The mitogen response of T cells enriched for OKT4+ helper-inducer cells is inhibited in manner similar to the response of unfractionated T cells. Thus, LTB4 and 15 HPETE stimulate both the function and the proliferation of the cytotoxic-suppressor T cell subset.

Arachidonic Acid↗
PubMed1985

Thymocyte cyclic AMP and cyclic GMP response to treatment with metabolites issued from the lipoxygenase pathway.

Evidence has been presented that cGMP is the second messenger for the lipoxygenase metabolites 15-HETE and LTB4 in the mouse splenocyte and thymocyte. Incubation of splenocytes with 10(-7) to 10(-9) M 15-HETE caused a slight decrease in cAMP levels and an increase in cGMP levels after 10 to 20 min. Mature PNA-, immature PNA+, and whole thymocytes treated with 10(-7) to 10(-10) M 15-HETE and 10(-11) M LTB4 showed an approximately 100% increase in cGMP production. In mixed lymphocyte reactions, 15-HETE- and LTB4-treated PNA+, PNA-, and whole thymocyte populations inhibited thymidine uptake by fresh allostimulated splenocytes. These results demonstrate that the eicosanoid-induced generation of suppressor cells follows a rise in lymphocyte cGMP levels.

Animals↗
PubMed1984

Effect of irradiation on human T-cell proliferation: low dose irradiation stimulates mitogen-induced proliferation and function of the suppressor/cytotoxic T-cell subset.

Unfractionated human T cells exposed to 10-50 rad of X irradiation incorporated less [3H]thymidine than nonirradiated T cells when subsequently cultured with PHA or Con A. The cytotoxic/suppressor T-cell subset, isolated as either OKT8(+) or OKT4(-) cells, demonstrated significantly enhanced [3H]thymidine incorporation in PHA- or Con A-stimulated cultures after exposure to 10-50 rad, compared to unirradiated cells, while the proliferation of the OKT4(+) helper/inducer subset was inhibited by low dose irradiation. It has been previously reported that approximately 30% of the cytotoxic/suppressor subset also stains with OKM1. When the cytotoxic/suppressor subset was further subdivided into OKT4(-), OKM1(+), and OKT4(-), OKM1(-) cells, proliferation of the OKT4(-), OKM1(+) population was inhibited by exposure to 25 rad while proliferation of the OKT4(-), OKM1(-) population was stimulated. The increase in proliferation of the cytotoxic/suppressor T-cell subset after low dose irradiation is paralleled by an increase in suppressor activity of these cells. T cells exposed to 25 rad and then cultured with Con A for 48 hr caused greater inhibition of IgG production when added to fresh autologous lymphocytes stimulated by pokeweed mitogen than did unirradiated cells. Thus, low dose irradiation enhances both the proliferation and function of the human suppressor T-cell subset.

Adult↗
PubMed1984

High efficiency capillary column-gas chromatography mass spectrometry: analysis of the lipoxygenase pathway in eukaryot cells.

Lipoxygenases are ubiquitous enzymes able to oxygenate polyunsaturated fatty acids. This metabolic pathway leads to hydroperoxides, hydroxyepoxyene compounds and leukotrienes. Using high performance gas chromatography prior to mass spectrometry, we studied the activity of the lipoxygenases from mouse peritoneal macrophages. Further studies on mechanism of biosynthesis of hydroxyepoxyene compounds were successfully carried out using 18O2 labelled precursors.

Animals↗
PubMed1984

Specific binding of 15 HETE to lymphocytes. Effects on the fluidity of plasmatic membranes.

Specific binding of mouse lymphocytes for 15 HETE was examined by incubating cells with [14C]-15 HETE, 1 X 10(-8) to 1 X 10(-10)M. It was observed that the specific binding of radiolabeled 15 HETE is a function of time, of temperature and is modified by Ca2+ and dithiothreitol. When a fluorescent probe was embedded in the phospholipid core of the lymphocyte membrane and its motion analysed by fluorescence polarization, it was observed that 15 HETE increases the viscosity of the plasmatic membrane.

Animals↗
PubMed1984

Immunosuppression induced in vivo by 15 hydroxyeicosatetraenoic acid (15 HETE).

We have investigated the in vivo effects of 15 HETE on C57Bl/6 (H-2b) mice injected IP daily with this product. After that the 15 HETE treated animals and the controls were challenged in vivo by DBA/2 (H-2d) cells. Splenocytes from 15 HETE injected animals were either stimulated in vitro by lectins or cocultivated with DBA/2 irradiated splenocytes. It was observed that the response of splenocytes from in vivo treated animals is weaker than the control's response. The data suggest that 15 HETE induce the generation of suppressor cells.

Animals↗
PubMed1983

Hydroperoxyeicosatetraenoic acids. Potent inhibitors of lymphocyte responses.

Arachidonic acid can be transformed into a series of HPETEs by the lipoxygenase enzyme activity of mouse peritoneal macrophages. These resulting HPETEs inhibit some mouse lymphocyte responses. When mice are injected with 15-L-HPETE, their splenocytes show a decreased [3H]thymidine uptake after lectin stimulation.

Animals↗