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M Labeta

Publications and source records attributed to M Labeta.

9 recordsLinked to original sources
PubMed1998

Down-regulation of surface monocyte lipopolysaccharide-receptor CD14 in patients on cardiopulmonary bypass undergoing aorta-coronary bypass operation.

OBJECTIVES: Major operative trauma like aorta-coronary bypass operation may lead to postoperative immunodisturbance, putting the patient at an increased risk for infection and sepsis. The monocyte/macrophage system and the endotoxin receptor CD14 are important in the early recognition and elimination of invading bacteria. The aim of this study was to analyze changes in membrane-associated CD14 and soluble CD14 during and after cardiac involving cardiopulmonary bypass. METHODS: We studied numbers of leukocytes, monocytes, and monocyte subpopulations, expression of monocyte membrane-associated CD14 and plasma levels of soluble CD14 in 10 patients (63 +/- 8 years of age), who underwent elective cardiopulmonary bypass. RESULTS: Cardiopulmonary bypass induced marked postoperative monocytosis, which was maximal 20 hours after the operation (485 +/- 242 cells/microl before, 1080 +/- 264 cells/microl 20 hours after surgery). Expression of membrane-associated CD14 on classical CD14++ monocytes decreased significantly by 40%, reaching a nadir 20 hours after surgery (p < 0.05). At the time of maximal membrane-associated CD14 suppression, the levels of soluble CD14 measured by enzyme-linked immunosorbent assay were clearly increased (3.2 +/- 1.0 microg/ml before versus 5.6 +/- 1.0 microg/ml 20 hours after, p < 0.001). No significant change of the percentage of small (alpha) and large (beta) forms of soluble CD14 was found. CONCLUSIONS: Cardiopulmonary bypass leads to reduced membrane-associated CD14 expression on peripheral blood monocytes and increased levels of soluble CD14 through shedding or secretion of membrane-associated CD14 from the cell surface. These findings indicate that bypass is associated with significant monocyte activation.

Blotting, Western↗
PubMed1992

A ligand-epitope in vitro analysis of major histocompatibility determinants expressed on B and T lymphocytes.

Human histocompatibility leucocyte antigen (HLA)-specific monoclonal antibody probes were used to determine the affinity constant, and cell-surface density of HLA class I and class II determinants. The measurements were estimated for single-cell units of B-lymphoblastoid cell line (B-LCL) and cloned activated T cells in different functional states. Each HLA subset showed unimodal affinity constant values for the interaction with the corresponding HLA-specific antibodies. Such values ranged between 2.2 x 10(7) M-1 (class I) and 4.0 x 10(7) M-1 (class II) for different histocompatibility epitopes. In both B and T cells there was a rank order of epitope expression, class I being highly expressed (5 x 10(6) epitopes/cell) followed by DR, DQ and DP, (1.1-3.0 x 10(6) epitopes/cell). Suppressive clones carrying functionally defined stimulating determinants previously designated 'DY' carried similar numbers of DR, DQ and DP binding sites to DY- non-suppressive clones, but showed selective increases of class II determinants reactive with broad class II-specific antibodies. The results are discussed in the context of the functional consequences of different patterns of HLA epitope expression in immune responses.

Antibodies, Monoclonal↗
PubMed1990

Major histocompatibility complex (MHC) protein analysis by optimised two-dimensional electrophoretic methods.

Human histocompatibility molecules HLA-Class I and Class II (DR, DQ, DP) were analysed using three two-dimensional protocols: nonequilibrium pH gradient electrophoresis (NEPHGE), isoelectric focusing-acidic gradient (IEF-AG) and isoelectric focusing-basic gradient (IEF-BG). The three methods differ in their carrier ampholyte combinations and electrophoretic conditions. They provide different pH gradients and therefore different electrofocusing profiles. The NEPHGE protocol was adequate for separating proteins across a broad range of pI mobilities, i.e. 4.4 pH units between the acidic and the basic end. In contrast, the IEF-AG and the IEF-BG protocols gave a separation power across a narrow pH range, 1.9 and 1.7 pH units respectively. Thus, whereas the NEPHGE protocol provides a tool for a global major histocompatibility complex (MHC) antigen profile analysis, the IEF-AG and -BG allows one to investigate subcomponents of the individual MHC chains. For example, NEPHGE analysis of the HLA Class I heavy chain revealed a single spot. However, IEF-BG revealed the presence of six equidistantly spaced spots spanning a short pH gradient with identical molecular weight. Similar improved resolution was seen for the HLA-DR, DQ, and DP molecules. The IEF acidic gradient was adequate for separating the alpha chain; the IEF basic gradient gave better resolution of the beta chains. This data provides a baseline set of conditions for both analytical and preparative MHC protein studies prior to amino acid sequencing.

Alleles↗
PubMed1988

Novel HLA class II-associated structural patterns in coeliac disease and type I diabetes.

Cell membrane antigens were precipitated from EBV transformed cell lines by a monomorphic DR monoclonal antibody. Three mutually exclusive patterns with two glycoproteins (g25 and g28) that had not been previously identified, were observed. The first, g25+/g28- was found in all cell lines from 40 healthy individuals; a second, g25-/g28- was found in 4/7 coeliac and 2/4 IDDM patients and a third, g25+/g28+ was found in 3/7 coeliac and 1/4 IDDM patients. RFLP analysis with Class II alpha and beta chain probes and several restriction enzymes did not correlate with either of the disease associated patterns. Several possibilities regarding the identity and mode of action of the two polypeptides are described.

Antibodies, Monoclonal↗
PubMed1986

The asymmetric IgG non-precipitating antibody. Localization of the oligosaccharide involved, by concanavalin A interaction.

Binding to Con A-Sepharose 4B of the low-affinity Fab fragment from sheep IgG1 anti-Dnp non-precipitating antibody was previously determined. This communication reports the results obtained when the concanavalin A interaction with Fd' fragments and L chains from non-precipitating and precipitating antibodies was examined. When Fd' fragments and L chains from non-precipitating and precipitating antibodies were tested as inhibitors of the binding of 125I-labelled concanavalin A to guinea pig erythrocytes, inhibition of such binding was only achieved by Fd' fragments from non-precipitating antibodies. Forty eight per cent of this Fd' fragment was bound by Con A-Sepharose 4B. From these results and our previous studies we conclude that mannose and/or glucose residues must be present and exposed at the Fd' fragment from the low-affinity Fab arm of sheep IgG1 anti-Dnp non-precipitating antibody. Glycosylation differences may explain the difference in precipitation behaviour of the 2 types of antibody.

Animals↗
PubMed1986

Serological biochemical and functional characterisation of three different HLA-DR monoclonal antibodies derived from C57BL6 mice.

C57BL6 mice which do not express I-E gene products were immunised with EBV transformed human B cell lines to generate MoAbs. Three hybridoma supernatants which initially reacted with the immunising donor cell but not a T cell line lacking Class II antigens were further investigated. I-D SDS-PAGE patterns of molecules precipitated by the three supernatants from a cell membrane lysate were characteristic of HLA-Class II alpha and beta chains. Two-dimensional analysis established the specificity of the supernatants as HLA-DR specific. This was confirmed by the reaction patterns with Class II mutant deletant cell lines. In both ELISA and cytotoxicity one reacted with all lymphoblastoid cell lines tested, one reacted with all except two that were DR7 homozygous and the third reacted strongly only with cells that were DR3. All three antibodies were cytotoxic to both peripheral blood lymphocytes and EBV transformed B cell lines. The DR3 specific MoAb (IgG2a) was suitable as a typing reagent. The DR3 reactive MoAb specifically inhibited stimulation by a Dw3 HTC and the other two MoAbs inhibited all HTCs tested. These findings are consistent with the view that certain determinants responsible for the Dw specificities are carried on the DR molecules.

Animals↗
PubMed1986

HLA-DQ molecular heterogeneity in HLA-DR4-Dw4 consanguineous cell lines.

Two-dimensional gel analysis (NEPHGE) of the molecules precipitated by the HLA-DR monomorphic antibody L243 showed a single and identical alpha chain spot from two consanguineous cell lines, BM14 and MCF. The latter was derived from a rheumatoid arthritis patient. No apparent structural polymorphism of the HLA-DR beta chains was detected. The data suggests that the HLA-DR4 haplotype expresses one alpha chain and up to four beta chains. The electrophoretic pattern of the HLA-DQ molecules precipitated with the monomorphic antibody TU22 revealed clear differences between BM14 and MCF. These differences were mainly in the beta chain profiles. Four acidic beta chains were found with the MCF cell line wheras only three beta chains at different isoelectric points were found with the BM14 cell line. The data obtained in this study argue for a considerable heterogeneity of the HLA-DQ antigens detected at the molecular level.

Arthritis, Rheumatoid↗
PubMedDate not supplied

The expression of murine Qa region gene product(s) in L cell transformants.

The cosmid H3.5, containing genes mapping to the murine H-2 Qa region, was used to transfect L cells by the calcium phosphate co-precipitation method. The resultant transfected cells expressed a Qa-like determinant as detected by an immune serum raised against the transfectant cells and Qa specific monoclonal antibodies. Two-dimensional gel analysis revealed the expression of a class I-like heavy chain with a similar molecular mass to the Qa2 antigens of the positive strain B10 and B10.A but with a different isoelectric point. The cosmid H3.5 spans 40 kb of DNA and contains at least one complete Qa region gene which encodes the Qa-like determinant detected in this study.

Animals↗