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Biomedical subjects

A Colombatti

Publications and source records attributed to A Colombatti.

At least 19 recordsLinked to original sources
PubMed2006

Use of reflexology foot massage to reduce anxiety in hospitalized cancer patients in chemotherapy treatment: methodology and outcomes.

AIM: To examine the effectiveness of reflexology foot massage in hospitalized cancer patients undergoing second or third chemotherapy cycles. BACKGROUND: Since the late-1970s, studies have been conducted to assess the efficacy of behavioural and relaxation approaches in controlling nausea/vomiting, anxiety and other side-effects associated with chemotherapy. METHODS: The study consisted of 30 patients being admitted to the oncology unit at a Scientific Research Hospital in Italy. Only 15 of the 30 participants received therapeutic massage. The subjects' self-reports of anxiety (measured by the Spielberger State-Trait Anxiety Inventory) were recorded before, after and 24 hours after the intervention. RESULTS: There was an average decrease of 7.9 points on the state-anxiety scale in the treatment group and of 0.8 points in the control group (P < 0.0001). CONCLUSIONS: Reflexology foot massage can be considered a support treatment used in combination with traditional medical treatments and executed by an expert, qualified person to help cancer patients receiving chemotherapy feel better and also cope better with their disease.

Adolescent↗
PubMed2005

p27(kip1) functional regulation in human cancer: a potential target for therapeutic designs.

The mitotic cell cycle is a tightly regulated process that ensures the correct division of one cell into two daughter cells. Progress along the different phases of the cell cycle is positively regulated by the sequential activation of a family of serine-threonine kinases called CDKs (Cyclin Dependent Kinases). Their activity is counteracted by small proteins known as CDK inhibitors (CKI) that ensure the correct timing of CDK activation in the different phases of the cell cycle. The present review will deal with the role of one of this CKI, p27(kip1), in human cancer, focusing in particular on the mechanisms underlying its functional inactivation in tumor cells. p27(kip1) protein downregulation is usually achieved by proteasomal degradation and is often correlated to a worse prognosis in several types of human cancers, resulting in the reduction of disease free and overall survival. More recently, it has been proposed that p27(kip1) protein, rather than degraded, can be functionally inactivated. The mechanisms and the implications of these two types of p27(kip1) deregulation will be discussed and some potential therapeutic approaches targeting p27(kip1) functions will be proposed.

Animals↗
PubMed2001

Isolation and characterization of EMILIN-2, a new component of the growing EMILINs family and a member of the EMI domain-containing superfamily.

EMILIN (elastin microfibril interfase located Protein) is an elastic fiber-associated glycoprotein consisting of a self-interacting globular C1q domain at the C terminus, a short collagenous stalk, an extended region of potential coiled-coil structure, and an N-terminal cysteine-rich domain (EMI domain). Using the globular C1q domain as a bait in the yeast two-hybrid system, we have isolated a cDNA encoding a novel protein. Determination of the entire primary structure demonstrated that this EMILIN-binding polypeptide is highly homologous to EMILIN. The domain organization is superimposable, one important difference being a proline-rich (41%) segment of 56 residues between the potential coiled-coil region and the collagenous domain absent in EMILIN. The entire gene (localized on chromosome 18p11.3) was isolated from a BAC clone, and it is structurally almost identical to that of EMILIN (8 exons, 7 introns with identical phases at the exon/intron boundaries) but much larger (about 40 versus 8 kilobases) than that of EMILIN. Given these findings we propose to name the novel protein EMILIN-2 and the prototype member of this family EMILIN-1 (formerly EMILIN). The mRNA expression of EMILIN-2 is more restricted compared with that of EMILIN-1; highest levels are present in fetal heart and adult lung, whereas, differently from EMILIN-1, adult aorta, small intestine, and appendix show very low expression, and adult uterus and fetal kidney are negative. Finally, the EMILIN-2 protein is secreted extracellularly by in vitro-grown cells, and in accordance with the partial coexpression in fetal and adult tissues, the two proteins shown extensive but not absolute immunocolocalization in vitro.

Amino Acid Sequence↗
PubMed2001

Laminin isoforms 8 and 10 are primary components of the subendothelial basement membrane promoting interaction with neoplastic lymphocytes.

To determine whether subendothelial laminins (LNs) could be implicated in the extravasation of neoplastic lymphocytes, we have examined the distribution of a number of LN isoforms in human vascular structures of adult individuals and have assayed the ability of the isolated LN molecules to promote adhesion of lymphoma and leukemic cells in vitro using a novel cell adhesion assay, CAFCA, Centrifugal Assay for Fluorescence-based Cell Adhesion (E. Giacomello et al., Biotechniques, 26: 758-762, 1999; P. Spessotto et al., Methods Mol. Biol., 139: 321-343, 2000). The use of previously characterized LN chain-specific antibodies showed that the vast majority of the smaller vascular compartments, known to correspond to sites of lymphocyte transmigration, expressed the subunits involved in the structuring of 9 of the 12 LN isoforms known to date. Eight LN isoforms (i.e., LN-1, -2, -4, -5, -8, -9, -10, and -11) and four naturally occurring LN complexes were isolated from various tissues and cultured cells by combined gel filtration, ion exchange, and immunoaffinity chromatographies, and the identity/composition of the isolated LNs/LN complexes was asserted by immunochemical means and amino-acid sequencing. Notwithstanding the widespread colocalization of LN isoforms, a panel of neoplastic B- and T-cell lines and lymphocytes isolated from patients affected by chronic lymphocytic B-cell leukemia attached preferentially and with high avidity to purified LN-8, purified LN-10, and LN-10-containing protein complexes, whereas lymphocytes derived from patients diagnosed with acute lymphocytic leukemia failed to bind to these LNs. All of the tested neoplastic lymphocytes failed to adhere to the isolated LN-1, LN-4, LN-9, and LN-11 and attached moderately well to purified LN-2 and LN-5. The interaction of transformed lymphocytes with LNs was cation-dependent and interchangeably mediated by the alpha3beta1 and alpha6beta1 integrins. The degree of engagement of the two LN receptors was dependent upon their relative levels of cell surface expression, whereas, irrespective of the phenotype, lymphocytes deprived of either of these receptors were incapable of LN binding. The findings suggest that LN-8 and LN-10 may act in an independent or complementary fashion as primary components of the endothelial basement membrane favoring the interaction of extravasating neoplastic lymphocytes. Thus, our results would demonstrate that different LN isoforms may evoke diverse cellular responses in different cell types and that this divergence may be the basis for the redundancy of LN distribution in a number of vascular structures.

Animals↗
PubMed2000

EMI, a novel cysteine-rich domain of EMILINs and other extracellular proteins, interacts with the gC1q domains and participates in multimerization.

The N-terminal cysteine-rich domain (EMI domain) of EMILIN-1 is a new protein domain that is shared with two proteins (multimerin and EMILIN-2) and with four additional database entries. The EMI domains are always located at the N-terminus, have a common gene organization, and belong to proteins that are forming or are compatible with multimer formation. The potential role of the EMI domain in the assembly of EMILIN-1 was investigated by the two-hybrid system. No reporter gene activity was detected when EMI-1 was co-transformed with the C-terminal gC1q-1 domain excluding a head-to-tail multimerization; conversely, a strong interaction was detected when the EMI-1 domain was co-transformed with the gC1q-2 domain of EMILIN-2.

Amino Acid Sequence↗
PubMed2000

Self-assembly and supramolecular organization of EMILIN.

The primary structure of human Elastin microfibril interface-located protein (EMILIN), an elastic fiber-associated glycoprotein, consists of a globular C1q domain (gC1q) at the C terminus, a short collagenous stalk, a long region with a high potential for forming coiled-coil alpha helices, and a cysteine-rich N-terminal sequence. It is not known whether the EMILIN gC1q domain is involved in the assembly process and in the supramolecular organization as shown for the similar domain of collagen X. By employing the yeast two-hybrid system the EMILIN gC1q domains interacted with themselves, proving for the first time that this interaction occurs in vivo. The gC1q domain formed oligomers running as trimers in native gels that were less stable than the comparable trimers of the collagen X gC1q domain since they did not withstand heating. The collagenous domain was trypsin-resistant and migrated at a size corresponding to a triple helix under native conditions. In reducing agarose gels, EMILIN also migrated as a trimer, whereas under non-reducing conditions it formed polymers of many millions of daltons. A truncated fragment lacking gC1q and collagenous domains assembled to a much lesser extent, thus deducing that the C-terminal domain(s) are essential for the formation of trimers that finally assemble into large EMILIN multimers.

Cell Line↗
PubMed2000

Bidirectional induction of the cognate receptor-ligand alpha4/VCAM-1 pair defines a novel mechanism of tumor intravasation.

Engagement of cell surface adhesion receptors with extracellular constituents and with cellular counter-receptors is crucial for the extravasation of blood-borne neoplastic cells and their seeding at distant sites; however, the early events of tumor dissemination-ie, the intravasation step(s)-have been largely neglected. A role for the alpha4beta7 integrin was hypothesized to explain the high leukemogenicity exhibited by one (NQ22) among several T-cell lymphomas studied. To clarify the mechanisms of early aggressivity, the behavior of highly and poorly leukemogenic cell lines were compared in vitro. Cocultivation of physically separated leukemic cells with resting endothelial cells resulted in the up-regulation of VCAM-1 expression. NQ22 cells expressed mRNA of different cytokines that up-regulate VCAM-1 and at higher levels than cells of a nonaggressive lymphoma, and they migrated more efficiently through an activated endothelial cell layer. With the use of neutralizing antibodies against interferon-gamma, granulocyte macrophage colony-stimulating factor, and tumor necrosis factor (TNF)-alpha, it was determined that TNF-alpha is one of the soluble factors released by NQ22 cells involved in the up-regulation of VCAM-1. The finding that vascular cells within the early local growth were strongly positive for VCAM-1 indicated that NQ22 cells could activate endothelial cells also in vivo. Finally, cocultivation of preleukemic alpha4(-)NQ22 cells with TNF-alpha-activated endothelial cells induced the expression of alpha4 integrins on the former cells. Reciprocal up-regulation and engagement of alpha4/VCAM-1 pairs determined the sequential transmigration and intravasation steps, and similar mechanisms might affect the aggressivity of human T lymphoblastic lymphomas.

Animals↗
PubMed2000

An 'environment to nucleus' signaling system operates in B lymphocytes: redox status modulates BSAP/Pax-5 activation through Ref-1 nuclear translocation.

The Ref-1 (also called APE or HAP1) protein is a bifunctional enzyme impacting on a wide variety of important cellular functions. It acts as a major member of the DNA base excision repair pathway. Moreover, Ref-1 stimulates the DNA-binding activity of several transcription factors (TFs) through the reduction of highly reactive cysteine residues. Therefore, it represents a mechanism that regulates eukaryotic gene expression in a fast way. However, it has been demonstrated that external stimuli directly act on Ref-1 by increasing its expression levels, a time-consuming mechanism representing a paradox in terms of rapidity of TF regulation. In this paper we demonstrate that this is only an apparent paradox. Exposure of B lymphocytes to H(2)O(2)induced a rapid and sustained increase in Ref-1 protein levels in the nucleus as evaluated by both western blot analysis and by pulse-chase experiments. A time course, two color in situ immunocytochemistry indicated that the up-regulation of Ref-1 in the nucleus at <30 min was primarily the consequence of translocation of its cytoplasmic form. This early nuclear accumulation is effective in modulating the DNA-binding activity of the B cell-specific activator protein BSAP/Pax-5. In fact, EMSA experiments demonstrate that a transient interaction with Ref-1 up-regulates the DNA-binding activity of BSAP/Pax-5. Moreover, in a co-transfection experiment, Ref-1 increased the BSAP/Pax-5 activating effect on an oligomerized BSAP/Pax-5 binding site of the CD19 promoter by 5- to 8-fold. Thus, Ref-1 mediates its effect by up-regulating the DNA-binding activity of BSAP/Pax-5, accounting for a new and fast outside/inside pathway of signaling in B cells.

B-Lymphocytes↗
PubMed2000

Structure, chromosomal localization, and promoter analysis of the human elastin microfibril interfase located proteIN (EMILIN) gene.

Elastin microfibril interfase-located protein (EMILIN) is an extracellular matrix glycoprotein abundantly expressed in elastin-rich tissues such as the blood vessels, skin, heart, and lung. It occurs with elastic fibers at the interface between amorphous elastin and microfibrils. In vitro experiments suggested a role for EMILIN in the process of elastin deposition. This multimodular protein consists of 995 amino acids; the domain organization includes a C1q-like globular domain at the C terminus, a short collagenous stalk, a region containing two leucine zippers, and at least four heptad repeats with a high potential for forming coiled-coil alpha-helices and, at the N terminus, a cysteine-rich sequence characterized by a partial epidermal growth factor-like motif and homologous to a region of multimerin. Here we report the complete characterization of the human and murine EMILIN gene, their chromosomal assignment, and preliminary functional data of the human promoter. A cDNA probe corresponding to the C terminus of EMILIN was used to isolate two genomic clones from a human BAC library. Sequencing of several derived subclones allowed the characterization of the whole gene that was found to be about 8 kilobases in size and to contain 8 exons and 7 introns. The internal exons range in size from 17 base pairs to 1929 base pairs. All internal intron/exon junctions are defined by canonical splice donor and acceptor sites, and the different domains potentially involved in the formation of a coiled-coil structure are clustered in the largest exon. The 3'-end of the EMILIN gene overlaps with the 5'-end of the promoter region of the ketohexokinase gene, whose chromosomal position is between markers D2S305 and D2S165 on chromosome 2. A 1600-base pair-long sequence upstream of the translation starting point was evaluated for its promoter activity; five deletion constructs were assayed after transfection in primary chicken fibroblasts and in a human rhabdomyosarcoma cell line. This analysis indicates the existence of two contiguous regions able to modulate luciferase expression in both cell types used, one with a strong activatory function, ranging from positions -204 to -503, and the other, ranging from positions -504 to -683, with a strong inhibitory function.

5' Untranslated Regions↗
PubMed2000

The EMILIN protein family.

The EMILINs are a new family of glycoproteins of the extracellular matrix. The prototype of this family is the chicken EMILIN that was originally identified in extracts of aortas; it was then found to be widely distributed in several tissues associated with elastin and localized at the interface between amorphous elastin and microfibrils. Based on peptide sequences, chicken and human cDNAs coding for EMILIN were isolated by RT/PCR by screening kidney and heart cDNA libraries. By using a C-terminal fragment of human EMILIN-1 as a bait in the yeast two-hybrid system, a second family member, EMILIN-2, has also been isolated. EMILINs are characterized by a C-terminal gC1q globular domain, a short collagenous sequence, a long coiled-coil region and a new cysteine-rich N-terminal domain that can be considered a hallmark of the family being present also in multimerin. The gene for EMILIN-1 was mapped on chromosome 2p23 overlapping with the promoter region of the ketohexokinase gene. The gC1q domain of EMILIN-1 can form relatively stable and compact homotrimers and this association is then followed by a multimeric assembly of disulfide-bonded protomers. Recombinant EMILIN-1 purified from the supernatant of 293 cells represents a very efficient ligand for cell adhesion of several cell types.

Animals↗
PubMed2000

Monoclonal antibody detection of naphthalene dioxygenase from Pseudomonas aeruginosa 2NR.

A monoclonal antibody, designated mAb alpha(CT), was generated against a peptide of the ISP(NAP) alpha-subunit of the naphthalene dioxygenase (NDO) enzyme of Pseudomonas aeruginosa. Since NDO expression is induced by aromatic hydrocarbons, its detection is important as a tool for environmental biomonitoring. This antibody is highly specific and works well both in an indirect ELISA assay and Western Blot analysis, allowing the detection of Pseudomonas spp. expressing the NDO inducible enzyme. The detection threshold for the ELISA assay developed in this work was 10(4) colony forming units (cfu) per ml. Thus, this mAb could represent a powerful tool to test for pollutants in soil, groundwater, and other natural environments.

Amino Acid Sequence↗
PubMed2000

Elastic fiber proteins in the glomerular mesangium in vivo and in cell culture.

BACKGROUND: Glomerular capillaries of the mammalian kidney are exposed to high intraluminal hydrostatic pressures and require elastic constraint to maintain size, shape, and integrity. Previous morphological and functional studies indicated that the extracellular matrices of glomeruli, that is, basement membrane and mesangial matrix, contribute to glomerular resilience and mechanical stability. Immunofluorescence microscopy findings demonstrated elastic fiber components to be located in the renal vasculature, including glomeruli. The aim of this study was to clarify the exact glomerular localization, composition, and cellular production of these proteins. METHODS: We examined the renal distribution of the elastic fiber proteins fibrillin-1, emilin, microfibril-associated glycoproteins (MAGPs) 1 and 2, latent transforming growth factor-binding protein-1 (LTBP-1), and elastin using immunohistology and immunoelectron microscopy of human, rat, and mouse kidneys. In mesangial cell cultures, we also studied the expression and extracellular deposition of such proteins by use of Northern blotting and immunocytochemistry. RESULTS: Fibrillin-1, emilin, MAGPs 1 and 2, and LTBP-1 were present in glomeruli of mouse, rat, and human kidney, where they were located predominantly in the mesangial extracellular matrix underlying glomerular endothelium and basement membrane. Several of these proteins, as well as elastin, were also expressed in the renal vasculature. While elastin localized to the glomerular vascular pole in afferent and efferent arterioles extending to Bowman's capsule, it was not found in the glomerular capillary tuft. Cultured mesangial cells of rat, mouse, and human kidneys expressed mRNAs of fibrillin-1, emilin, MAGP-2, and elastin, and the respective proteins localized within and outside of mesangial cells, as shown by immunocytochemistry. mRNA expression of fibrillin-1, emilin, and elastin was strong in quiescent mesangial cells; their gene expression was further up-regulated by transforming growth factor-beta1, while it was transiently reduced when cells were exposed to mitogenic 10% fetal calf serum and platelet-derived growth factor. CONCLUSIONS: These findings demonstrate that specific elastic fiber proteins are produced and secreted by mesangial cells. This process is regulated by growth factors. Their abundance in the extracellular matrix of the mesangium is in keeping with the concept that elastic fiber proteins contribute to the mechanical stability and elastic strength of the glomerular capillary tuft.

Animals↗
PubMed2000

Avian neural crest cell migration is diversely regulated by the two major hyaluronan-binding proteoglycans PG-M/versican and aggrecan.

It has been proposed that hyaluronan-binding proteoglycans play an important role as guiding cues during neural crest (NC) cell migration, but their precise function has not been elucidated. In this study, we examine the distribution, structure and putative role of the two major hyaluronan-binding proteoglycans, PG-M/versicans and aggrecan, during the course of avian NC development. PG-M/versicans V0 and V1 are shown to be the prevalent isoforms at initial and advanced phases of NC cell movement, whereas the V2 and V3 transcripts are first detected following gangliogenesis. During NC cell dispersion, mRNAs for PG-M/versicans V0/V1 are transcribed by tissues lining the NC migratory pathways, as well as by tissues delimiting nonpermissive areas. Immunohistochemistry confirm the deposition of the macromolecules in these regions and highlight regional differences in the density of these proteoglycans. PG-M/versicans assembled within the sclerotome rearrange from an initially uniform distribution to a preferentially caudal localization, both at the mRNA and protein level. This reorganization is a direct consequence of the metameric NC cell migration through the rostral portion of the somites. As suggested by previous in situ hybridizations, aggrecan shows a virtually opposite distribution to PG-M/versicans being confined to the perinotochordal ECM and extending dorsolaterally in a segmentally organized manner eventually to the entire spinal cord at axial levels interspacing the ganglia. PG-M/versicans purified from the NC migratory routes are highly polydispersed, have an apparent M(r) of 1,200-2,000 kDa, are primarily substituted with chondroitin-6-sulfates and, upon chondroitinase ABC digestion, are found to be composed of core proteins with apparent M(r )of 360-530, 000. TEM/rotary shadowing analysis of the isolated PG-M/versicans confirmed that they exhibit the characteristic bi-globular shape, have core proteins with sizes predicted for the V0/V1 isoforms and carry relatively few extended glycosaminoglycan chains. Orthotopical implantation of PG-M/versicans immobilized onto transplantable micromembranes tend to 'attract' moving cells toward them, whereas similar implantations of a notochordal type-aggrecan retain both single and cohorts of moving NC cells in close proximity of the implant and thereby perturb their spatiotemporal migratory pattern. NC cells fail to migrate through three-dimensional collagen type I-aggrecan substrata in vitro, but locomote in a haptotactic manner through collagen type I-PG-M/versican V0 substrata via engagement of HNK-1 antigen-bearing cell surface components. The present data suggest that PG-M/versicans and notochordal aggrecan exert divergent guiding functions during NC cell dispersion, which are mediated by both their core proteins and glycosaminoglycan side chains and may involve 'haptotactic-like' motility phenomena. Whereas aggrecan defines strictly impenetrable embryonic areas, PG-M/versicans are central components of the NC migratory pathways favoring the directed movement of the cells.

Aggrecans↗
PubMed2000

Humanized antibodies as potential drugs for therapeutic use.

Antibodies have been used therapeutically to treat a variety of clinical conditions. The introduction of monoclonal antibodies (mAb) and, recently, engineered antibodies has greatly refined and expanded the therapeutic potential of this modality of treatment. Expanded use will depend on improvement in their efficacy (affinity and specificity), demonstration of their safety, and reduction of their immunogenicity depending on the size, suboptimal biodistribution and pharmacokinetics. To surmount these problems the molecules have to be redesigned and the basic issues of how monoclonal antibodies kill cells reinvestigated. The review will survey the literature for humanized antibodies in clinical trials and the perspective of the use of mAbs or engineered antibodies in clinical practice.

Animals↗
PubMed1999

Anti-V3 and anti-IgG antibodies of healthy individuals share complementarity structures.

It was recently shown that antibodies reactive with a peptide from the tip of the HIV-1NY5 gp120 V3 loop (V3 peptide) are present not only in sera of HIV-positive patients but also in sera of healthy HIV-negative individuals. In the present study, we show that V3 peptide reactive antibodies are predominantly IgM in sera of HIV negative individuals and that a fraction of the IgG anti-V3 antibodies exhibit features of autoantibodies. These antibodies were purified by chromatography on IgG-sepharose columns from sera as well as from purified IgG anti-V3 antibodies. A higher IgG anti-V3 reactivity was detected in autoantibody preparations from HIV-positive sera as compared with the reactivity of sera and purified antibodies from HIV-negative individuals. This was confirmed by solid phase binding of IgG anti-V3 antibodies both to V3 and to human IgG F(ab')2 antigens. The autoantibodies did not bind to peptides that share sequence similarity with V3 peptide indicating a high epitope specificity. The detection of antibodies against HIV epitopes in HIV-negative individuals may suggest that anti-V3 antibodies after HIV infection represent at least in part a secondary immune response.

Antibodies, Anti-Idiotypic↗
PubMed1999

EMILIN, a component of the elastic fiber and a new member of the C1q/tumor necrosis factor superfamily of proteins.

EMILIN (elastin microfibril interface located protein) is an extracellular matrix glycoprotein abundantly expressed in elastin-rich tissues such as blood vessels, skin, heart, and lung. It occurs associated with elastic fibers at the interface between amorphous elastin and microfibrils. Avian EMILIN was extracted from 19-day-old embryonic chick aortas and associated blood vessels and purified by ion-exchange chromatography and gel filtration. Tryptic peptides were generated from EMILIN and sequenced, and degenerate inosine-containing oligonucleotide primers were designed from some peptides. A set of primers allowed the amplification of a 360-base pair reverse transcription polymerase chain reaction product from chick aorta mRNA. A probe based on a human homologue selected by comparison of the chick sequence with EST data base was used to select overlapping clones from both human aorta and kidney cDNA libraries. Here we present the cDNA sequence of the entire coding region of human EMILIN encompassing an open reading frame of 1016 amino acid residues. There was a high degree of homology (76% identity and 88% similarity) between the chick C terminus and the human sequence as well as between the N terminus of the mature chick protein where 10 of 12 residues, as determined by N-terminal sequencing, were identical or similar to the deduced N terminus of human EMILIN. The domain organization of human EMILIN includes a C1q-like globular domain at the C terminus, a collagenous stalk, and a longer segment in which at least four heptad repeats and a leucine zipper can be identified with a high potential for forming coiled-coil alpha helices. At the N terminus there is a cysteine-rich sequence stretch similar to a region of multimerin, a platelet and endothelial cell component, containing a partial epidermal growth factor-like motif. The native state of the recombinantly expressed EMILIN C1q-like domain to be used in cell adhesion was determined by CD spectra analysis, which indicated a high value of beta-sheet conformation. The EMILIN C1q-like domain promoted a high cell adhesion of the leiomyosarcoma cell line SK-UT-1, whereas the fibrosarcoma cell line HT1080 was negative.

Amino Acid Sequence↗
PubMed1999

Human immunodeficiency virus V3 peptide-reactive antibodies are present in normal HIV-negative sera.

A structural relation between consensus sequences of the portion of HIV-1 gp120 involving the V3 loop (V3 peptide) and the variable domains of human immunoglobulin members of the VH-III gene family was proposed to trigger an imbalance of the idiotypic network during the course of HIV infection. Thus, the repertoires of immunoglobulins in healthy individuals should contain antigenic determinant(s) complementary to particular V3 loop epitope(s). In this study we investigated the specific binding to the V3 peptide of antibodies present in sera of HIV-positive and of clinically normal HIV-negative subjects. Two groups of HIV-positive sera differing in antibody titers to V3 peptide, arbitrarily referred here as high- and low-reactive HIV-positive sera, were distinguished on the basis of an ELISA. Antibodies were affinity purified on V3 peptide and their titers in both HIV-negative and low-reactive HIV-positive sera were nearly superimposable and much lower than the titers of those from high-reactive HIV-positive sera. Also, the quality of the two groups of antibodies differed: much higher amounts of soluble V3 peptide were needed to partly compete the binding of antibodies from HIV-negative sera to insoluble V3 peptide as compared with those from HIV-positive sera, suggesting that the latter had higher affinity for V3 peptide. All of the affinity-purified antibodies bound poorly to unrelated peptides, even to those sharing sequence similarity with the V3 peptide. The present observations suggest that in HIV infection antigen-driven affinity maturation of preimmune immunoglobulins with idiotypes complementary to V3 epitope(s) participating in physiological autoreactivity might be at work.

Amino Acid Sequence↗