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Biomedical subjects

J Vives

Publications and source records attributed to J Vives.

At least 91 records · Page 5Linked to original sources
PubMed1987

Unfractionated human thymocytes have a lower proliferative capacity than CD3-4-8- ones but have a similar capacity for expression of interleukin 2 receptors and production of interleukin 2.

CD3-4-8- and unfractionated thymocytes were compared for their capacity to proliferate, to express interleukin 2 (IL-2) receptor, and to secret IL-2. Phorbol ester and Ca2+ ionophore were used as mitogens. CD3-4-8- thymocytes responded vigorously when stimulated with phorbol ester in the presence of IL-2 or in combination with Ca2+ ionophore. In contrast, unfractionated thymocytes responded weakly when stimulated with either of these mitogens. Surprisingly, however, the stimulation of these populations with either phorbol ester plus IL-2 or phorbol ester plus ionophore induced a high and similar level of IL-2 receptor expression in both thymocyte populations. A similar level of IL-2 secretion in both populations was also obtained when they were stimulated with a combination of phorbol ester plus ionophore. These results suggest that during the maturation process, the majority of thymocytes lose their capacity to be activated by some mitogens, although they maintain their capacity to secrete IL-2 and to express the IL-2 receptor.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1987

Hybridoma process: ultrastructural cytology of different stages.

In order to define the ultrastructure of the hybridoma cell and to learn more about the plasmocytic differentiation process, a scanning (SEM) and transmission (TEM) electron microscopy study of several cell types involved in the production of monoclonal antibodies was performed. Cells of the three different stages in hybridoma process were studied. These cells included NS/1 murine myeloma cells, 40-3A4 in vitro cultured hybridoma and 33-1D2 ascitic tumor hybridoma cells. A stereological analysis of the Sv parameter (surface of RER per volume unit of cytoplasm) was performed in the murine myeloma line, the in vitro cultured hybridoma and the ascitic tumor hybridoma. In order to comparatively evaluate the plasmocytic differentiation of these cells the same methodology was applied to splenic lymphocytes from immunized mouse and to mature human myelomatous plasma cells. As expected, during the hybridoma process, a progressive increase in the amount of RER was detected. This was in contrast with the surface characteristics of the cells which become progressively smooth when the hybridoma was cloned, either in vitro or in vivo. From these results it can be inferred that the amount of RER is a more reliable parameter than surface blebs as a morphological element indicative of plasmocytic differentiation. On the other hand, numerous viral particles were present not only in murine myeloma line but also in hybridoma clones secreting monoclonal antibodies.

Animals↗
PubMed1986

New experimental criteria for optimization of solid-phase antigen concentration and stability in ELISA.

A peroxidase saturation technique for the determination of coating antigen concentration necessary to saturate polystyrene plates with a wide range of different antigens is described. The same technique has also been used to compare the stability of antigen-polystyrene bonds for native and denaturated antigens. Furthermore, the inappropriate selection of solid-phase antigen concentration and its influence on ELISA results is analyzed and an experimental criterion to select the optimum antigen concentration is proposed. Two different antigens, BSA-Ar and hydatid antigen, were used for ELISA determination of specific antibodies as a model system. Optimum solid-phase antigen concentration was determined by two different methods: peroxidase saturation, in which binding of peroxidase to non-antigen-occupied polystyrene surface sites was used to evaluate the degree of coating by antigen; chequer-board titration, using several immune sera of different affinity. Optimum antigen concentration selected by chequer-board titration using low affinity sera was similar to that selected with peroxidase saturation. On the other hand, lower antigen concentration would be selected by chequer-board titration using high affinity sera. For this reason, the concentrations of low affinity antibodies would be underestimated using the chequer-board titration. These results indicate that peroxidase saturation should be used to avoid avidity-dependent artifacts in ELISA.

Animals↗
PubMed1986

Influence of HBV replication and delta agent superinfection on T cell subsets and killer (Leu 7+) in chronic hepatitis B virus infection.

Peripheral blood T-lymphocyte subsets and cells reacting for Leu 7 antigen, which identifies a subset of killer and natural killer cells, have been examined in 32 patients chronically infected by the hepatitis B or D viruses (HBV, HDV) and in 28 normal subjects. The T8+ lymphocytes were increased and the T4/T8 ratio was decreased in patients with HBV replication (identified by the presence of HBcAg in liver and HBV-DNA in serum) and in patients with HDV infection (HDAg in liver). These patients had more active liver disease than patients without evidence of viral replication, B or D, who showed normal lymphocyte counts. Leu 7+ lymphocytes were also increased in patients with viral replication and active disease and correlated positively with alaninaminotransferase serum levels. These observations suggest the participation of both T8+ and Leu7+ cells in the pathogenesis of liver cell injury in HBsAg-positive chronic liver disease.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1986

Affinity maturation in the arsonate system: lack of dominance of high-affinity antibody subpopulations.

Affinity maturation was studied by the analysis of the kinetics of the appearance of antibody subpopulations with different affinities during the immune response, using an hapten-inhibition ELISA. The immune response in KLH-Ar-immunized A/J mice was used as a model system. Five antibody subpopulations of different affinity (10(3)-10(7) M-1) could be detected, the relative concentrations of which changed during affinity maturation. The high-affinity antibody subpopulations did not represent the major fraction at any stage during affinity maturation. The appearance of the highest affinity subpopulation (10(7) M-1), despite exhibiting relative concentrations no higher than 12%, produced an important increase in average affinity. On the other hand, its disappearance at the end of the maturation process could explain the average affinity decrease observed at this stage. Our results indicate that affinity maturation cannot be explained by the dominance of high-affinity clones, as proposed by Siskind & Benacerraf (1969). The increase in affinity could rather be due to the progressive appearance of low percentages of high-affinity clones, which are not present in the primary response and never become dominant.

Animals↗
PubMed1985

Interaction of DNA with lysine-rich polypeptides and proteins. The influence of polypeptide composition and secondary structure.

Using X-ray diffraction we have studied fibres obtained from complexes of DNA with lysine-rich polypeptides and with proteins that have different conformations, to ascertain whether the conformations of the polypeptides and the DNA are maintained upon interaction. Substances investigated include N-acetyl-Lys-Ala-Tyr-Ala-Lys-ethylamide, random poly(Leu50, Lys50), sequential poly(Leu-Lys), poly(Val-Lys), poly(Ala-Lys), poly(Lys-Ala-Ala-Lys), poly(Lys-Ala-Ala), poly(Lys-Leu-Ala), poly(Lys-Ala-Gly), protein phi 0 from sea cucumber spermatozoa, histone H1 and two fragments of this protein obtained by chemical cleavage. In general, the B form of DNA with ten base-pairs per helical turn is maintained upon interaction at high levels of humidity. The A form is never observed; it appears to be forbidden in a protein environment. No evidence for transition into any novel DNA conformation has been observed, although the B form is altered in some cases, in particular upon dehydration. Such alteration occurs always in the sense of tightening the double helix, so that the number of base-pairs per helical turn diminishes. The polypeptides may interact with DNA in both the alpha and beta conformations. We have found different types of complexes in which either a monolayer or a double layer of beta-pleated sheets is intercalated between layers of DNA molecules. Alternatively, the polypeptide chain may be wrapped around the DNA, following one of the grooves. The polypeptide conformation may be either maintained or changed upon interaction. The charge density of the polypeptide is an important parameter of the interaction. When it matches the charge density of the DNA, the polypeptide conformation is maintained in most cases; otherwise it is modified. The globular part of histone H1 gives a unique X-ray pattern upon interaction, indicative of a loss of order of DNA in the complex. On the other hand, the C-terminal part of histone H1 gives a very well-ordered complex, similar to a nucleoprotamine, in spite of its lower charge density.

Amino Acid Sequence↗
PubMed1985

Lymphocytotoxic antibodies in primary biliary cirrhosis.

Sera of 30 patients with primary biliary cirrhosis (PBC) and 72 normal subjects matched for age and sex were examined for the presence of lymphocytotoxic antibodies (LCAs) against B and T cells at 4 degrees C and 37 degrees C. Patients were prospectively screened for: Sjögren's syndrome, scleroderma, Hashimoto's thyroiditis, and rheumatoid arthritis, in which LCAs have been described. Seventeen patients with PBC (56.6%) had LCAs against B cells as compared with only 11 of the 72 normal subjects (P less than 0.001). Five PBC patients (16.6%) also reacted against T cells as compared with none in control group (P less than 0.01). Clinical and biochemical features and the histological stage of PBC were similar in patients with and without LCA. Sjögren's syndrome was present in 13 patients--two with scleroderma and another with Hashimoto's thyroiditis. No patient had rheumatoid arthritis. The prevalence of LCAs was similar in PBC patients with or without autoimmune associated disease (54% vs 59%). We conclude that in PBC a high incidence of LCA is unrelated to the presence of an associated disease. LCA in PBC might be a nonspecific marker of an immune disorder.

Adult↗
PubMed1985

Application of ELISA-inhibition to Aspergillus antigen standardization for immunodiagnosis.

An inhibition ELISA method was used to test culture filtrate antigens of Aspergillus fumigatus for the avidity of antibodies to them. Four different culture media were used to check the ability of this assay to distinguish between similar antigenic preparations. Differences between antigens exhibiting similar crossed immunoelectrophoresis patterns were observed by inhibition ELISA.

Antibodies, Fungal↗
PubMed1985

Multiple myeloma with monoclonal IgG and IgD of lambda type exhibiting, under treatment, a shift from mainly IgG to mainly IgD.

A patient with multiple myeloma (MM), who initially presented with a predominant IgG lambda and a minor IgD lambda paraprotein pattern, is described. After chemotherapy, levels of the IgD lambda protein increased and the IgG lambda levels decreased. The following results were obtained when serum IgD was predominant. In the bone marrow, there were three plasma cell populations: a major one containing only delta chains, a minor one containing only gamma chains, and another minor one containing both delta and gamma chains. All these plasma cell populations contained lambda chains. Stimulation of circulating mononuclear cells with pokeweed mitogen (PWM) achieved differentiation of circulating B lymphocytes into plasma cells: 30% with only cytoplasmic delta lambda chains and 10% with only cytoplasmic gamma lambda chains. These IgG-containing plasma cells showed cytoplasmic reactivity with rabbit antiserum raised against monoclonal IgD which was shown to contain specificities recognizing both delta chains and idiotypic determinants present in both serum IgD lambda and IgG lambda. Circulating B lymphocytes were 'monoclonal': almost all expressed surface delta lambda chains, and a small proportion of them expressed both delta gamma and lambda chains. High levels of IgD were detected in the supernatants of all cultures, but high concentrations of IgG were only detected in those from PWM-stimulated cultures with very low levels of IgM and IgA. These findings suggest that plasma cells producing either IgD or IgG were derived from a common B-cell clone. Double paraproteinaemia exhibiting a shift in immunoglobulin production from IgG to IgD has not been previously described.

Antibodies, Monoclonal↗
PubMed1984

An antiplatelet monoclonal antibody that inhibits ADP and epinephrine-induced aggregation.

A monoclonal antibody (Mab) named EDU-3, was produced by fusing splenocytes from one Balb/c mouse, immunized with a mixture of platelets and non-T cells from heparinized human peripheral blood, with the HAT-sensitive myeloma line P3-NS1/1.Ag4.1. By indirect immunofluorescence (IF) it was seen that this Mab reacted with all normal human platelets and bone marrow megakaryocytes, but did not react with lymphoid cells from normal donors, or platelets from Glanzmann's thrombasthenia (GT) patients. Immunoprecipitation and SDS-PAGE experiments demonstrated that this Mab recognized an epitope on the IIb-IIIa glycoprotein complex (GPC). EDU-3 inhibited platelet aggregation and release of ATP induced by ADP and epinephrine. Aggregation induced by arachidonic acid, ristocetin and bovine factor VIII were not inhibited by EDU-3. The difference between EDU-3 and other Mab directed against the IIb-IIIa GPC is discussed.

Adenosine Diphosphate↗
PubMed1984

Direct measurement of antibody affinity distribution by hapten-inhibition enzyme immunoassay.

A rapid, simple and reliable technique for determining the affinities of antibody subpopulations in a complex mixture is described. The principle of this method is that antigen conc can be represented as the amount of antigen immobilized on the polystyrene surface of a microwell containing a fixed vol of diluted antibody. Thus, by measuring the proportion of antibody bound to different wells coated with varying amounts of antigen, it is a straightforward matter to calculate an affinity distribution. We have verified that: (1) the amount of antigen bound to a polystyrene plate is proportional to the concn of antigen used for sensitization and follows a typical saturation curve; (2) the antibodies bound to plates sensitized with low concns of antigen are of higher affinity than those bound to plates sensitized with high concns of antigen; (3) an apparent affinity constant (aK) is defined as the reciprocal concn of free hapten required for 50% inhibition of antibody binding to immobilized antigen; (4) the aK determined by this method is in close agreement with the intrinsic affinity constant (K) measured by fluorescence quenching or the Farr assay; and (5) that during the course of immunization in vivo there is a clear shift to higher-affinity antibody subpopulations.

Animals↗
PubMed1983

Sequential evaluation of general immunocompetence in gynecologic cancer.

A sequential evaluation of general immunocompetence was performed in 70 previously untreated patients with gynecologic cancer. Immunologic evaluations were made prior to any therapy and repeated every 3-4 months for 3 years or until patients died of disease. Cell-mediated immunity was investigated by delayed hypersensitivity to intradermal skin test antigens (STA) and by contact sensitization to 2,4-dinitrofluorobenzene (DNFB). Serum immunoglobulin determinations were performed to evaluate humoral immunity. Compared with age-matched controls, there was impairment of cell-mediated response to both STA and DNFB in patients with locally invasive and disseminated cancer but not in those with preinvasive cancer. There was a progressively impaired reactivity with clinical progression of disease independently of histological type of neoplasm. Sequential evaluations revealed that variations in immune reactivity occurred that also correlated with the patient's clinical course. Significant changes in immunoglobulin levels, an increase in IgG and IgA, and a decrease in IgM, were observed in the cancer groups as compared with age-matched healthy female controls. However, neither initial values nor sequential determinations of immunoglobulins were related to the clinical course of gynecologic cancer.

Adult↗
PubMed1983

Monoclonal antibody against HLA-Aw32 + A25. Is HLA-Aw32 an allele with no unique antigenic determinant?

In the present paper we describe the production and characterization of a monoclonal antibody (Mab) recognizing HLA-Aw32 + A25 antigens. NS1 murine myeloma cells were fused with splenocytes from a BALB/c mouse immunized with normal human peripheral blood (PB) lymphocytes of phenotype A1, Aw32; B7,B37,Cw-,Cw-;DR2,DRw10. Supernatants were first screened against Cr51-labeled immunizing cells by complement dependent cytotoxicity 51Cr-CDC). Cultures identified as producing cytotoxic antibodies were subcultured and the supernatants tested against a selected panel of HLA typed cells by the NIH microcytotoxicity method. One culture producing antibody reacting with an HLA polymorphism was detected. This hybrid, designated CATA 1, was cloned twice by limiting dilution and obtained in ascitic form. Specificity of CATA 1 Mab was evaluated against a panel of 120 PB T cells from normal donors. CATA 1 reacted with cells bearing HLA-A25 or HLA-Aw32 antigens. In addition, a reaction was observed with a cell of phenotype A2,Aw31; B17,Bw49. Isoelectric focusing revealed the monoclonal nature of CATA 1, with immunofixation identifying it as an IgG molecule. Absorption studies have demonstrated that CATA 1 recognizes a common determinant on HLA-A25 and HLA-Aw32. The finding that this Mab recognizes the same CREG as alloantisera against HLA-Aw32 suggests that this antigen has no unique epitopes.

Alleles↗