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G Fontán

Publications and source records attributed to G Fontán.

At least 19 recordsLinked to original sources
PubMed1998

Cellular adhesion mediated by factor J, a complement inhibitor. Evidence for nucleolin involvement.

Factor J (FJ) is a complement inhibitor that acts on the classical and the alternative pathways. We demonstrated FJ-cell interactions in fluid phase by flow cytometry experiments using the cell lines Jurkat, K562, JY, and peripheral blood lymphocytes. FJ bound to plastic plates was able to induce in vitro adhesion of these cells with potency equivalent to fibronectin. As evidence for the specificity of this reaction, the adhesion was blocked by MAJ2, an anti-FJ monoclonal antibody, and by soluble FJ. Attachment of the cells required active metabolism and cytoskeletal integrity. The glycosaminoglycans heparin, heparan sulfate, or chondroitin sulfates A, B, and C inhibited to varying degrees the binding of FJ to cells, as did treatment with chondroitinase ABC. In the search for a putative receptor, a protein of 110 kDa was isolated by affinity chromatography, and microsequence analysis identified this protein as nucleolin. Confocal microscopy evidenced the presence of nucleolin in cell membrane by immunofluorescence with monoclonal (D3) and polyclonal anti-nucleolin antibodies in Jurkat cells. The interaction FJ-nucleolin was evidenced by Western blot and enzyme-linked immunosorbent assay. Furthermore, purified nucleolin and D3 inhibited adhesion of Jurkat cells to immobilized FJ, suggesting that the interaction was specific and that nucleolin mediated the binding.

Antibodies, Monoclonal↗
PubMed1998

Phenotypical and functional characterization of Herpesvirus saimiri-immortalized human major histocompatibility complex class II-deficient T lymphocytes.

CD8+ T lymphocytes from two unrelated cases of MHC class II deficiency were immortalized in vitro using Herpesvirus saimiri. In both cases, a lack of expression of surface MHC class II molecules was ascertained, whereas variable defects were shown for MHC class I, CD74 (invariant chain) and LAG-3 (an MHC class II ligand). The functional analysis of both H. saimiri-immortalized T-cell lines revealed the existence of a proliferation impairment in response to anti-CD3 but not to other surface or transmembrane stimuli. Further characterization of this functional defect indicated that it was not associated with impaired early activation events (like calcium flux) but, rather, with certain late events, like the induction of IL-2. H. saimiri-immortalized T cells may be valuable in studying the biological role of MHC class II molecules in activated human T cells.

Cell Transformation, Viral↗
PubMed1997

Elevated factor J levels in synovial fluid from patients with inflammatory arthropathies.

Factor J (FJ) is a complement inhibitor that is able to regulate in vitro both the classical and alternative human complement pathways. In the search of its biological significance, we have analyzed FJ levels in synovial fluid from patients with different arthropathies, in which IL-6 levels had been previously measured. The pathologies included in this study were: rheumatoid arthritis (RA) (n = 21), crystal deposition diseases (CDD) (n = 6), osteoarthritis (OA) (n = 23), spondyloarthritis (SpA) (n = 3) and other inflammatory arthropathies (OIA) (n = 4). We found a good correlation between IL-6 and FJ levels (r = 0.33, p = 0.0132) in the 57 processed samples. Synovial fluids had high levels of IL-6 (median: 3000 pg/ml). Besides, we found that FJ levels were elevated (241 +/- 429 micrograms/ml) when compared with NHS (5.32 +/- 2.82 micrograms/ml). Considering OA patients as control group for non-inflammatory situation, we found that FJ levels were significantly elevated in inflammatory patients only if RA patients were excluded. Furthermore, there were also significant differences with CDD patients. In addition, we have examined the presence of this inhibitor in synovial fluid by Western blot after running gels at acid pH and electrophoretical transference at the same pH. In these experiments, we evidenced the presence of a cationic protein immunoreactive with polyclonal and monoclonal anti-FJ antibodies. In conclusion, FJ levels are elevated in pathological synovial fluids. FJ could be an acute phase reactant as other molecules present in the synovial fluid, or could be shed from extracellular matrix as a consequence of the high enzymatic activity present in the articular fluid or as a response to the inflammatory stimulus.

Antibodies, Monoclonal↗
PubMed1997

Recurrent infectious diseases in human CD53 deficiency.

We report a familiar syndrome of recurrent heterogeneous infectious diseases, caused by bacteria, fungi, and viruses, which has as its only detectable defect the lack of CD53 antigen expression in neutrophils. All other assays ruled out known causes of recurrent infectious diseases due to either leukocyte adhesion or phagocytosis defects. CD53 belongs to the transmembrane-4 superfamily of proteins, which are a novel group of membrane proteins implicated in growth regulation and cell motility and possibly cell adhesion. We postulate that defects in these membrane proteins can be clinically manifested as complex recurrent infections.

Adolescent↗
PubMed1996

Factor J, an inhibitor of the classical and alternative complement pathway, does not inhibit esterolysis by factor D.

Factor J (FJ) is an inhibitor of the classical and alternative complement pathways. On the classical pathway factor J disrupts the C1 component, and on the alternative pathway, factor J disrupts the C3 convertase (C3b,Bb) by a direct interaction of FJ with the components C3b and Bb. The aim of this work was to verify whether FJ could have any effect on factor D proteolytic activity since previous experiments could not rule out an eventual inhibition by factor J on factor D enzymatic activity. For this purpose, the reactivity of serine proteinase factor D was determined by using two peptide thioester substrates, Z-Lys-SBzl.HCl and Z-Lys-Arg-SBzl.2HCl, in the presence and in the absence of factor J. Kinetic studies evidenced that FJ did not affect the enzymatic activity of factor D in any case.

Complement C1 Inactivator Proteins↗
PubMed1996

A novel X-linked gene, DDP, shows mutations in families with deafness (DFN-1), dystonia, mental deficiency and blindness.

In 1960, progressive sensorineural deafness (McKusick 304,700, DFN-1) was shown to be X-linked based on a description of a large Norwegian pedigree. More recently, it was shown that this original DFN-1 family represented a new type of recessive neurodegenerative syndrome characterized by postlingual progressive sensorineural deafness as the first presenting symptom in early childhood, followed by progressive dystonia, spasticity, dysphagia, mental deterioration, paranoia and cortical blindness. This new disorder, termed Mohr-Tranebjaerg syndrome (referred to here as DFN-1/MTS) was mapped to the Xq21.3-Xq22 region2. Using positional information from a patient with a 21-kb deletion in chromosome Xq22 and sensorineural deafness along with dystonia, we characterized a novel transcript lying within the deletion as a candidate for this complex syndrome. We now report small deletions in this candidate gene in the original DFN-1/MTS family, and in a family with deafness, dystonia and mental deficiency but not blindness. This gene, named DDP (deafness/ dystonia peptide), shows high levels of expression in fetal and adult brain. The DDP protein demonstrates striking similarity to a predicted Schizosaccharomyces pombe protein of no known function. Thus, is it likely that the DDP gene encodes an evolutionarily conserved novel polypeptide necessary for normal human neurological development.

Abnormalities, Multiple↗
PubMed1996

[Radiologic digestive manifestations in patients with antibody deficiency].

UNLABELLED: In order to establish a relationship between radiological and clinical data and/or early diagnosis of the complications frequently found in patients with hypogammaglobulinemia, we carried out gastrointestinal series (GIS) in 47 patients mean age 22.5 years with hypogammaglobulinemia or primary antibody deficiencies. RESULTS: 15 patients did not show any radiological abnormalities. Nodular lymphoid hyperplasia (NLH) was found in 23 cases. None of the patients with NLH had gastrointestinal symptoms. Radiologic signs of malabsorption were present in 15 cases. 2 patients with radiologic signs of malabsorption (mean age 12 years) did have clinical or laboratory finding suggesting a malabsortive syndrome. Moreover, 2 patients showing clinical manifestations of malabsorption did not show any significant radiological findings. 4 patients were diagnosed of chronic atrophic gastritis (CAG) by means of endoscopy and gastric biopsy, whereas only in one of these cases GIS showed gastric fold atrophy, compatible with the pathologic diagnosis of CAG; 2 of these patients progressed to gastric cancer, a diagnosis that was done by endoscopy. CONCLUSIONS: We have observed that NLH is more frequent in patients with hypogammaglobulinemia than in the normal population, it is asymptomatic and may be diagnosed by radiological methods. The radiological findings of malabsorption do not correlate with the clinical data. A combination of endoscopy and gastric biopsy is the method of choice for the early diagnosis of atrophic gastritis and gastric cancer, since the radiological alterations found in GIS appear at late times. We conclude that GIS supplies few data to the study of digestive manifestations in patients with hypogammaglobulinemia, except in the case of NLH.

Adolescent↗
PubMed1995

[the early diagnosis of the vertical transmission of the human immunodeficiency virus type 1. The evaluation of diagnostic tests].

BACKGROUND: The early diagnosis of vertically transmitted human immunodeficiency virus infection cannot be based on the presence of specific serum antibodies since those of the maternal IgG class pass the placenta and may be detected in children for up to 18 months. Based on this fact, the aim of this study was to evaluate other techniques for early diagnosis of the infection applicable from birth in 306 children of infected mothers. METHODS: The production of in vitro antibodies, virus culture and polymerase chain reaction (PCR) were used. The sensitivity of the techniques was estimated in the 40 children diagnosed with human immunodeficiency virus infection and specificity was determined in the 266 uninfected children. RESULTS: The sensitivity for the production of in vitro antibodies was 62.0% at 3 months and 94.7% at 6 months; 90.4% and 88.2%, respectively, for the viral culture and 92.3% and 94.1%, respectively, for the PCR. The specificity of all the cases was higher than 89.4% although varied in relation to age. CONCLUSIONS: The combination of several diagnostic techniques provides better performance for the early diagnosis of vertical transmission of the human immunodeficiency virus. Given that viral culture takes longer to provide results and is more expensive, it is less recommendable for routine use, although the form of viral replication may be useful to establish the prognosis.

Aging↗
PubMed1995

Cell surface molecules related to factor J in human lymphoid cells and cell lines.

Factor J (FJ) is a cationic glycoprotein that is able to inhibit in vitro both the classical and alternative pathways of complement. FJ was purified to homogeneity from human urine by sequential chromatographic steps. To examine the expression of FJ in human cells we obtained mAbs against urine-purified FJ. Preliminary studies by immunocytochemistry revealed that one of the anti-FJ mAbs recognized cell surface components of certain cell lines, such as K562 and U937 cells, so we have focused subsequently on the detection of these homologue membrane-bound FJ Ags (FJ-h Ags) in cell lines of lymphoid (Ramos and Jurkat) and mieloyd (U937 and K562) origin, as well as in peripheral blood cells. The flow cytometry analysis of the examined cell lines revealed partial staining ranging from 10% (U937) to 29% (K562) positive cells. Flow cytometry of peripheral blood cells showed a positive staining in a small but consistent population of lymphocytes (mean = 11%, n = 17) but none at all on monocytes, granulocytes, erythrocytes, or platelets. Double Ab immunostaining of lymphocytes showed that the FJ-h positive population included mainly B lymphocytes (a mean of 63% CD19+ were FJ-h positive). When we analyzed peripheral blood lymphocytes from a patient with chronic lymphocytic leukemia B (95% CD19+/CD5+), the majority of these (55%) bore FJ-h on their surface. Acid strip of these cells did not abrogate the surface staining, which supports the finding that the Ag is tightly bound to the membrane. Immunoprecipitation from U937 cell lysates showed a single 65 kDa band under reducing conditions. FJ-h Ags purified from K562 and U937 cells displayed inhibitory activity in the functional EAC14 assay for the classical complement pathway, as did urine FJ, and they were recognized immunochemically by five different (one polyclonal and four monoclonal) anti-FJ Abs. In conclusion, FJ-homologues are present in the membranes of several human cell lines that show functional and antigenic characteristics similar to soluble urine FJ. They are also found in a small subset of peripheral blood lymphocytes, mainly B cells. The structural relationship between both soluble urine FJ and these membrane-bound FJ-h remains to be established.

Animals↗
PubMed1995

Antiperinuclear factor: a useful test for the diagnosis of rheumatoid arthritis.

The objective of this study was to determine: (1) the diagnostic value of antiperinuclear factor (APF), (2) the types of immunoglobulins involved in the reaction and (3) the presence of the antibody in paired samples of serum and synovial fluid (SF). We studied 408 serum samples from the following: healthy controls (n = 68), patients with rheumatoid arthritis RA; n = 160, 106 RF-positive and 54 RF-negative and patients with other rheumatic diseases (n = 180). We examined paired serum and SF samples in 27 patients (8 with RA and 19 with other rheumatic conditions). APF was determined by an indirect immunofluorescence assay. A group of 30 APF-positive serum samples was incubated with fluorescent-labelled antisera against IgG, IgM and IgA independently. APF was positive in 55.7% of patients with RF-positive RA, in 35.2% of patients with RF-negative RA, in 11.1% of patients with other rheumatic diseases and in 5.9% of healthy controls. Statistical differences were found between RF-positive RA and the other three groups (P = 0.02, P = 0.0001, P = 0.0001, respectively) and between RF-negative RA and the groups of other rheumatic diseases (P = 0.0001) and healthy controls (P = 0.005). The specificity of the test for RA was 90.2%. APF was present in three SF samples from RA patients (37.5%). The reaction was mediated by immunoglobulins of the IgG class in 100% of those tested, and, in addition, 30% were of IgA and 6.7% of IgM classes. We concluded that APF is a good diagnostic test that could be included in the classification criteria of RA, it can be present in SF and it is predominantly an antibody of the IgG class.

Adult↗
PubMed1995

Prognostic value of immunological data, in vitro antibody production, and virus culture in vertical infection with HIV-1.

The prognostic value of immunological indices, in vitro antibody production, and virus culture pattern at 3 months of age was estimated in 35 infants infected by HIV-1 from a cohort of 298 babies born to HIV-1 seropositive mothers and followed up from birth. At 1 year old, 15 of these infants were classified as stage P-1 (according to the Centers for Disease Control classification) seven were P-2A, and seven had AIDS. Significantly higher CD8 percentages, lower percentages and absolute value of CD4, and lower CD4/CD8 ratios at 3 months were observed in infants with severe symptoms at 1 year of age when compared with those who were asymptomatic at this age. Seventy seven per cent of infants with a 'rapid' virus culture when 3 months old had developed AIDS or had died by 1 year of age and only 8% of those with 'slow' virus culture had AIDS when 1 year old. Moreover, 100% of those who were asymptomatic at 1 year had a slow virus culture at 3 months. Significant statistical association was found between the virus replication pattern at 3 months and the clinical stage at 1 year of age.

Acquired Immunodeficiency Syndrome↗
PubMed1994

The inhibitory effect of factor J on the alternative complement pathway.

Factor J (FJ) is a cationic glycoprotein with inhibitory activity in C1, the first component of the classical complement pathway. This study demonstrates that FJ is able to regulate the activity of the alternative complement pathway. FJ inhibits the generation of fluid-phase and cell-bound alternative pathway C3 convertase, C3b,Bb (C3-cleaving enzyme). Thus, FJ interferes with the generation of alternative pathway C3 convertase when sheep erythrocytes bearing antibody and activated C3 and C4 (EAC4b,3b) are incubated with the individual complement components, factors B, D, and P. FJ accelerates the decay of C3 convertase with a time course similar to that of factor H, and when both regulators are present together, the decay of enzyme activity is faster than when they are added separately. Furthermore, FJ is able to inhibit the cleavage of C3 by factor B in a fluid-phase assay. FJ prevents the initiation of alternative pathway activation in "more stabilized systems" with well known activators of alternative pathway C3 convertase such as C3 nephritic factor (an autoantibody against alternative pathway C3 convertase), cobra venom factor, and rabbit erythrocytes. In these systems, FJ has no effect on C3 convertase stabilized by rabbit erythrocytes or cobra venom factor. In contrast, FJ promotes the dissociation of C3 convertase stabilized by C3 nephritic factor, but with much lower efficiency than in preventing initiation. Direct interaction of FJ with individual components of C3 convertase was shown by a solid-phase binding assay using plates coated with C3, C3b, B, Bb, or FJ. FJ inhibitory activity in the alternative pathway can be modulated by polyanions like heparin. FJ-mediated inhibition in the alternative complement pathway can be modified by surface interactions, as occurs during alternative pathway C3 convertase activation. Thus, when FJ is adsorbed by and eluted from hydroxylapatite and reverse-phase columns, its inhibitory effect on more stabilized systems is lost. This loss of inhibitory activity is fully reversed when FJ is rechromatographed on heparin-Sepharose or Sepharose columns. Taking into account these data, FJ may be included in the group of highly charged molecules that inhibit the activation of classical and alternative complement pathways (i.e. eosinophil major basic protein, protamine, and heparin).

Animals↗
PubMed1994

Isolation of cosmid and cDNA clones in the region surrounding the BTK gene at Xq21.3-q22.

A regional physical and transcription map involving yeast artificial chromosomes (YACs), cosmids, and cDNAs has been constructed for Xq21.3-q22 around the gene BTK (formerly atk or BPK) defective in X-linked agammaglobulinemia (XLA). With a positional cloning strategy employing direct cDNA selection, novel cDNAs were found to cluster in the region of approximately 100 kb flanking the XLA and alpha-galactosidase A loci. While these widely expressed transcripts are in the area known to contain CpG islands, a less evolutionarily conserved gene, located more than 130 kb distal of DXS178, maps to cosmid clones that could not be digested with rare-cutting restriction enzymes. The presence of transcribed sequences flanking the BTK allowed us to investigate their involvement in complex XLA phenotypes. Southern blot analysis using cDNA clones isolated from this region permitted us to exclude a contiguous deletion syndrome as an underlying defect in three patients with XLA and associated growth hormone deficiency. A single XLA patient with torsion dystonia and cosegregating X-linked deafness has been found with a deletion in the 3' part of BTK extending centromerically into the flanking expressed sequence DXS1274E. This suggests a possible involvement of the DXS1274E in this phenotype. The GenBank accession numbers for novel cDNA sequences are as follows: DXS1269E (L20773), DXS1271E (UO1923), DXS1273E (UO1925), and DXS1274E (UO1922).

Agammaglobulinaemia Tyrosine Kinase↗
PubMed1994

Factor J, an inhibitor of the complement classical pathway: the quantitation by an ELISA inhibition assay in normal human serum.

Factor J (FJ) is a protein present in human serum, with inhibitory activity against C1. Here we describe the quantitation of FJ in human serum by means of an ELISA inhibition assay. We have purified FJ from the urine of a normal donor following a previously published method with slight modifications. Polyclonal anti-FJ antibodies have been raised in rabbits immunized with a single dose of purified antigen injected in multiple sites. IgG from polyclonal FJ antiserum, coupled to a solid matrix (Affi-Prep gel) was able to adsorb purified FJ antigenically and functionally. Furthermore, anti-FJ specifically retained serum components antigenically related with urine FJ. Taking into account this reactivity, we have developed an inhibition enzyme-linked immunosorbent assay (ELISA) useful for measuring FJ levels in normal human serum. This immunoassay involves preincubating polyclonal anti-FJ with different dilutions of normal human serum to quantitatively reduce the antibody available to bind to purified FJ-coated microtiter plates. Binding of remaining antibody to the microtiter plate is measured spectrophotometrically using peroxidase-conjugated secondary antibody. Quantitation is accomplished by comparison with a known quantity of purified FJ. Conditions for optimization of this quantitative assay have been assessed, including trials with different blocking agents, of which nonfat milk gave the best results. Preliminary experiments showed the existence of paradoxical effects, that is, high nonspecific binding at high serum dilutions. We have eliminated these effects by including high ionic strength (0.4 M NaCl) in the sample incubation solution. Sensitivity and reproducibility parameters have also been established. FJ levels have been measured for the first time in sera from 86 healthy donors.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Factor J, a human inhibitor of complement C1, is a cationic, highly glycosylated protein.

Factor J (FJ) is a new inhibitor of the complement system. This work supports the fact that FJ is a cationic molecule (pI > or = 9.6 in native conditions, or pI = 8.1 in denaturing conditions) with a high sugar content (40%) that is able to interact with different lectins, suggesting a complex glycosylation. SDS impaired FJ migration in polyacrylamide gel electrophoresis. In Triton-acid-urea-polyacrylamide gel electrophoresis FJ migrated as a complex, dispersed molecule. In contrast, FJ after Smith degradation (dFJ) gave a single, smeared band of M(r) = 23.4 kDa in reducing SDS-PAGE. dFJ retained only 60% of the initial inhibitory activity of intact FJ. When digestions with different proteinases were performed, no modification of activity was observed. After beta-glucuronidase digestion, FJ lost 80% of its initial activity. Consequently, glycosylation plays an important role in the inhibitory activity of FJ.

Carbohydrate Sequence↗
PubMed1993

X-linked agammaglobulinemia and gastric adenocarcinoma.

BACKGROUND: The incidence and mortality rate for cancer in patients with primary immunodeficiency diseases have increased greatly. Lymphomas constitute more than 50% of tumors identified in the Immunodeficiency Cancer Registry, but solid tumors are frequent in these patients, especially gastric carcinomas. In addition to immunologic impairment, other local conditions such as chronic atrophic gastritis with intestinal metaplasia and pernicious anemia, usually observed in these patients, may play an important role in the genesis of gastrointestinal tumors. METHODS AND RESULTS: This report describes a 23-year-old patient with X-linked agammaglobulinemia who had previously documented chronic atrophic gastritis with intestinal metaplasia, pernicious anemia, and parasitization with Giardia lamblia in whom an adenocarcinoma of the stomach developed. CONCLUSION: The authors believe that it may be useful to perform a periodic gastrointestinal evaluation for all patients with primary immunodeficiencies to establish early detection and treatment of these tumors.

Adenocarcinoma↗