RESUMEN
Staphylococcal toxic shock syndrome (TSS) is an acute life threatening disease. The diagnosis can be made clinically based on diagnostic criteria. The clinical manifestations are caused in large part by there lease of high levels of T-cell-derived cytokines as a result of potent toxins, also called superantigens (SAg), produced by Staphylococcus aureus, but it is not clear which clinical symptoms/signs are strictly T-cell dependent. Here, we report on three adults with multiple myeloma (MM) presenting with S.aureus sepsis/shock, and two patients with typical TSS. The MM patients had compromised humoral immunity because of depression of normal immunoglobulin (Ig) levels at the expense of the M protein. In addition, their T cells were absent due to high dose chemotherapy initiated for bone marrow trans-plantation. The MM cases lacked mucosal hyperemia, erythroderma and desquamation, but were otherwise indistinguishable from the TSS cases. All patients grew S. aureus and in each case, SAg genes were detected by PCR. In several cases, the plasma contained biological SAg activity resulting in VP specific proliferation of indicator T cells in vitro. The same specific activity was observed with the supernatant fluids of S. aureus broth cultures from the respective bacterial isolates. This confirms the presence of bio-active toxins in the plasma but did not lead to full blown TSS when T cells were lacking.Thus, S. aureus sepsis/shock can be clinically distinguished from typical TSS, and we suggest that mucocutaneous manifestations of TSS are the most telling signs of massive T-cell-dependent cytokine release.
Asunto(s)
Mieloma Múltiple/complicaciones , Infecciones Oportunistas/diagnóstico , Choque Séptico/diagnóstico , Infecciones Estafilocócicas/diagnóstico , Linfocitos T/inmunología , Adulto , Células Cultivadas , Niño , Preescolar , Diagnóstico Diferencial , Femenino , Genes Codificadores de los Receptores de Linfocitos T , Humanos , Huésped Inmunocomprometido , Depleción Linfocítica , Masculino , Persona de Mediana Edad , Membrana Mucosa/irrigación sanguínea , Infecciones Oportunistas/complicaciones , Infecciones Oportunistas/microbiología , Choque Séptico/complicaciones , Choque Séptico/microbiología , Piel/patología , Infecciones Estafilocócicas/complicaciones , Infecciones Estafilocócicas/microbiología , Staphylococcus aureus/inmunología , Staphylococcus aureus/aislamiento & purificación , Superantígenos/sangre , Superantígenos/genética , Superantígenos/inmunologíaRESUMEN
We usually think of superantigens (SAg) as dangerous toxins that may cause toxic shock syndrome and death. Now, based on two papers in this issue of Immunity, it seems that we all have SAg genes within us, lying dormant and waiting to be activated under special circumstances.
Asunto(s)
Antígenos Virales/inmunología , Superantígenos/inmunología , Retrovirus Endógenos/inmunología , Humanos , Activación de Linfocitos , Virus del Tumor Mamario del Ratón/inmunología , Linfocitos T/inmunología , Virosis/inmunologíaRESUMEN
HIV induces CD4 down-regulation from the surface of infected cells by several independent mechanisms, suggesting an important biological role for this phenomenon. In vitro CD4 down-regulation generates T cells with a double-negative (DN) CD4(-)CD8(-) T cell receptor-alphabeta(+) phenotype. However, evidence that this down-regulation occurs in vivo in HIV-infected subjects is lacking, and viral load or viral production assays invariably focus on CD4(+) T cells. We show here that HIV infection can often be detected in sorted DN cells from peripheral blood and lymph nodes, even when plasma viral load is undetectable. DN T cells infected with HIV represented up to 20% of the cellular viral load in T cells, as determined by DNA PCR. In patients on successful highly active antiretroviral therapy, the viral load decreased in the plasma in CD4(+) and in DN T cells, suggesting that infected DN cells, like CD4(+) cells, contribute to viral production and are sensitive to highly active antiretroviral therapy. Indeed, HIV unspliced and multispliced RNAs were often detectable in DN T cells in spite of the small size of this subset. Infectious virus from DN T cells was transmitted efficiently in coculture experiments with uninfected T cell lymphoblasts, even when viral DNA in the DN cells was barely detectable. We conclude that a discrete population of infected DN T cells exists in HIV-positive subjects, even when the plasma viral load is undetectable. These cells may represent an important source of infectious virus.
Asunto(s)
ADN Viral/análisis , Infecciones por VIH/inmunología , VIH/genética , Linfocitos T/virología , Adulto , Fármacos Anti-VIH/uso terapéutico , Complejo CD3/inmunología , Antígenos CD4/inmunología , Recuento de Linfocito CD4 , Antígenos CD8/inmunología , División Celular , ADN Complementario/análisis , Regulación hacia Abajo , Quimioterapia Combinada , Ensayo de Inmunoadsorción Enzimática , Femenino , Genes gag/genética , Infecciones por VIH/genética , Humanos , Subgrupos Linfocitarios/inmunología , Masculino , Persona de Mediana Edad , Fenotipo , ARN Viral/análisis , Linfocitos T/metabolismo , Factores de TiempoRESUMEN
Superantigens have been implicated in a wide variety of human diseases. Yet, solid evidence for their role in pathogenesis is available only for Toxic Shock Syndrome and a few other conditions. This evidence is critically reviewed herein.
Asunto(s)
Infecciones/inmunología , Choque Séptico/inmunología , Superantígenos/inmunología , Animales , Humanos , Infecciones/microbiología , Infecciones/fisiopatología , Choque Séptico/microbiología , Choque Séptico/fisiopatologíaRESUMEN
CD8 T cells contain a distinct subset of CD8+ CD28- cells. These cells are not present at birth and their frequency increases with age. They frequently contain expanded clones using various TCRalphabeta receptors and these clones can represent >50% of all CD8 cells, specially in old subjects or patients with chronic viral infections such as HIV-1. Herein, it is shown that a large fraction of CD8+ CD28- cells expresses intracellular perforin by three-color flow cytometry, in particular when this subset is expanded. Together with their known ability to exert potent re-directed cytotoxicity, this indicates that CD8+ CD28- T cells comprise cytotoxic effector cells. With BrdU labeling, we show that CD8+ CD28- cells derive from CD8+ CD28+ precursors in vitro. In addition, sorted CD8+ CD28+ cells gave rise to a population of CD8+ CD28- cells after allo-stimulation. Moreover, ex vivo CD8+ CD28+ cells contain the majority of CD8 blasts, supporting the notion that they contain the proliferative precursors of CD8+ CD28- cells. CD95 (Fas) expression was lower in CD8+ CD28- cells, and this subset was less prone to spontaneous apoptosis in ex vivo samples and more resistant to activation-induced cell death induced by a superantigen in vitro. Thus, the persistence of expanded clones in vivo in the CD8+ CD28- subset may be explained by antigen-driven differentiation from CD8+ CD28+ memory precursors, with relative resistance to apoptosis as the clones become perforin(+) effector cells.
Asunto(s)
Antígenos CD28/metabolismo , Linfocitos T CD8-positivos/citología , Subgrupos de Linfocitos T/inmunología , Linfocitos T Citotóxicos/inmunología , Adulto , Anciano , Envejecimiento , Apoptosis , Linfocitos T CD8-positivos/inmunología , Diferenciación Celular , Células Clonales , Humanos , Glicoproteínas de Membrana/biosíntesis , Persona de Mediana Edad , Perforina , Proteínas Citotóxicas Formadoras de Poros , Receptores de Antígenos de Linfocitos T alfa-beta/inmunología , Superantígenos/inmunología , Subgrupos de Linfocitos T/citología , Linfocitos T Citotóxicos/citologíaRESUMEN
T cells infiltrating the rheumatoid arthritis (RA) joint are oligoclonal, implicating an Ag-driven process, but the putative joint-specific Ags remain elusive. Here we examine expression of selected EBV genes in RA synovia and find no abnormal expression in RA. DNA of CMV and EBV was detectable by PCR in the synovial tissue of RA. RNA of several latent and lytic EBV genes was also detectable. However, there were no differences in EBV gene expression in synovial tissues or peripheral blood when comparing RA with osteoarthritis, Gulf War syndrome, and other disease controls. RA synovia with highly expanded CD8 T cell clones reactive with defined EBV peptide Ags presented by HLA class I alleles lacked evidence of abnormal mRNA expression for the relevant EBV Ag (BZLF1) or lacked amplifiable mRNA (BMLF1). Thus, local production of EBV Ags in synovial tissues may not be the cause of the accumulation of T cell clones specific for these Ags. Instead, APCs loaded with processed EBV peptides may migrate to the synovium. Alternatively, EBV-specific T cells clones may be generated in other tissues and then migrate to synovia, perhaps due to cross-reactive joint-specific Ags or because of expression of homing receptors.
Asunto(s)
Antígenos Virales/inmunología , Artritis Reumatoide/virología , Epítopos de Linfocito T/inmunología , Regulación Viral de la Expresión Génica/inmunología , Herpesvirus Humano 4/genética , Membrana Sinovial/virología , Linfocitos T/virología , Artritis Reumatoide/inmunología , Artritis Reumatoide/patología , Células Clonales , Citomegalovirus/genética , ADN Viral/análisis , Herpesvirus Humano 4/inmunología , Herpesvirus Humano 6/genética , Herpesvirus Humano 7/genética , Herpesvirus Humano 8/genética , Humanos , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Membrana Sinovial/inmunología , Membrana Sinovial/patología , Linfocitos T/inmunologíaRESUMEN
Infection of T cells with HIV-1 induces loss of CD4 and HLA class I from the cell surface. In the present article we have investigated whether changes in expression of other cell surface molecules could be related to HIV infection. To detect HIV-infected cells at the single-cell level, peripheral blood lymphocytes were infected in vitro with HIV-HSA, a reporter virus encoding the murine heat-stable antigen. Expression of HSA on activated primary lymphocytes was an efficient indicator of productive infection. Expression of the majority of the cell surface proteins studied was unaffected by HIV infection (HLA class I, II, CD11a, CD18, CD25, CD27, CD28, CD29, CD30, CD31, CD38, CD44, CD45R0, CD49d, CD57, CD94, CD95, and CXCR4). However, phenotypic changes specific to the productively infected cells were detected. Expression of the CD4 molecule was progressively lost and this was closely associated with loss of CD62L expression, a molecule involved in T cell homing into the lymph nodes. By contrast, T cells productively infected with this T-tropic reporter virus were enriched for CD54, and for CCR5, the main coreceptor for M-tropic viruses. Given the roles of CD62L, CD54, and CCR5 in lymphocyte trafficking, these results suggest that cells productively infected with HIV might have altered homing patterns in vivo.
Asunto(s)
Antígenos CD/metabolismo , Antígenos CD4/metabolismo , VIH/metabolismo , Molécula 1 de Adhesión Intercelular/metabolismo , Selectina L/metabolismo , Glicoproteínas de Membrana , Receptores CCR5/metabolismo , Linfocitos T/inmunología , Linfocitos T/virología , Animales , Antígenos CD/genética , Antígeno CD24 , Células Cultivadas , Citometría de Flujo , Genes Reporteros/genética , VIH/genética , Humanos , Ratones , Fenotipo , Reacción en Cadena de la Polimerasa , Receptores Mensajeros de LinfocitosRESUMEN
Intestinal intraepithelial lymphocytes (iIEL) are primarily CD8 cells and most of them have a CD28- phenotype, the phenotype of effector cytotoxic T cells. We asked whether the predominance of CD8+CD28- T cells in the gut may result from peripheral blood T cells preferentially migrating to the iIEL compartment and adhering to iEC. Compared with CD4 cells, adhesion of resting CD8+ T cells to iEC cell lines was significantly higher. Adhesion could be blocked with a MoAb to gp180, a molecule expressed on iEC which is known to interact with CD8/lck. No significant difference in the level of adhesion was observed between CD8+CD28+ and CD8+CD28- T cells. Thus CD8 cells may preferentially migrate to the iIEL compartment, but loss of CD28 expression could occur in situ after migration. Consistent with this hypothesis, the CD8+CD28- cells became enriched after co-culturing T cells with iEC cell lines and primary iEC. Induction of the CD8+CD28- phenotype in cord blood and adult T cells was observed in co-cultures with iEC and also with mitogens and superantigens. In the latter case, CD28 down-modulation was seen specifically in the Vbeta subset targeted by the superantigen, indicating that loss of CD28 expression is a direct result of T cell receptor (TCR)-mediated stimulation. The combined results suggest that CD8+CD28- T cells are antigen experienced T cells, and that they may have a survival advantage in the presence of gut epithelial cells in vitro. This may contribute to the predominance of CD8+CD28- T cells in the iIEL compartment.
Asunto(s)
Linfocitos T CD8-positivos/inmunología , Mucosa Intestinal/inmunología , Adulto , Antígenos CD28/análisis , Linfocitos T CD8-positivos/citología , Adhesión Celular , Compartimento Celular , Muerte Celular/inmunología , Células Cultivadas , Técnicas de Cocultivo , Sangre Fetal , Humanos , Mucosa Intestinal/citología , Linfocitos T Citotóxicos/inmunologíaRESUMEN
Superantigens are defined as proteins that activate a large number of T cells through interaction with the Vbeta region of the T cell antigen receptor (TCR). Here we demonstrate that the superantigen produced by Mycoplasma arthritidis (MAM), unlike six bacterial superantigens tested, interacts not only with the Vbeta region but also with the CDR3 (third complementarity-determining region) of TCR-beta. Although MAM shares typical features with other superantigens, direct interaction with CDR3-beta is a feature of nominal peptide antigens situated in the antigen groove of major histocompatibility complex (MHC) molecules rather than superantigens. During peptide recognition, Vbeta and Valpha domains of the TCR form contacts with MHC and the complex is stabilized by CDR3-peptide interactions. Similarly, recognition of MAM is Vbeta-dependent and is apparently stabilized by direct contacts with the CDR3-beta region. Thus, MAM represents a new type of ligand for TCR, distinct from both conventional peptide antigens and other known superantigens.
Asunto(s)
Mycoplasma/inmunología , Receptores de Antígenos de Linfocitos T/metabolismo , Superantígenos/metabolismo , Antígenos Bacterianos/inmunología , Antígenos Bacterianos/metabolismo , Artritis Reumatoide/inmunología , Autoinmunidad/inmunología , Proteínas Bacterianas/inmunología , Proteínas Bacterianas/metabolismo , Linfocitos T CD4-Positivos/inmunología , Células Clonales/inmunología , Células Clonales/metabolismo , Clonación Molecular , Humanos , Ligandos , Complejo Mayor de Histocompatibilidad/inmunología , Mutagénesis/genética , Mycoplasma/química , Péptidos/química , Péptidos/inmunología , Péptidos/metabolismo , Receptores de Antígenos de Linfocitos T/química , Receptores de Antígenos de Linfocitos T/inmunología , Alineación de Secuencia , Superantígenos/inmunología , Transfección/genéticaRESUMEN
Superantigens encoded by the mouse mammary tumor virus can stimulate a large proportion of T cells through interaction with germline-encoded regions of the T cell receptor beta chain like the hypervariable region 4 (HV4) loop. However, several lines of evidence suggest that somatically generated determinants in the CDR3 region might influence superantigen responses. We stimulated T cells from donors differing at the BV6S7 allele with vSAG9 to assess the nature and structure of the T cell receptor in amplified T cells and to evaluate the contribution of non-HV4 elements in vSAG recognition. This report demonstrates that vSAG9 stimulation caused the expansion of TCR BV6-expressing T cells, although to varying degrees depending on the BV6 subfamily. The BV6S7 subfamily was preferentially expanded in all donors, but in donors homozygous for the BV6S7*2 allele, a significant number of BV6S5 T cells were amplified and showed a highly biased beta chain junctional region (BJ) and CDR3 usage. As CDR3 regions are involved in major histocompatibility complex (MHC)-peptide interaction, such a selection is highly suggestive of an intimate MHC-TCR interaction and would imply that the topology of the MHC-vSAG-TCR complex is similar to the one occurring during conventional antigen recognition.
Asunto(s)
Antígenos Virales/inmunología , Virus del Tumor Mamario del Ratón/inmunología , Receptores de Antígenos de Linfocitos T alfa-beta/metabolismo , Superantígenos/inmunología , Subgrupos de Linfocitos T/metabolismo , Secuencia de Aminoácidos , Animales , Antígenos Virales/metabolismo , Línea Celular , Humanos , Activación de Linfocitos , Complejo Mayor de Histocompatibilidad/genética , Complejo Mayor de Histocompatibilidad/inmunología , Virus del Tumor Mamario del Ratón/metabolismo , Ratones , Modelos Inmunológicos , Datos de Secuencia Molecular , Familia de Multigenes , Receptores de Antígenos de Linfocitos T alfa-beta/química , Receptores de Antígenos de Linfocitos T alfa-beta/genética , Superantígenos/metabolismo , Subgrupos de Linfocitos T/inmunologíaRESUMEN
The diversity of the human TCR repertoire in aging has been studied by examining the profiles of complementarity-determining region 3 (CDR3) sizes expressed by the BV families. The TCRBV CDR3 profile, which shows size heterogeneity in young adult humans, is significantly restricted in aged humans. Clonal T cell expansions were identified using a PCR-based approach, in one or more BV families from all 14 healthy persons over the age of 65 that we studied. CD4+ T cell expansions were identified in 8 of 11 donors and CD8+ T cell expansions in 7 of 10 donors. These clonal expansions were stable during a 2-year period. Interestingly, more than half of the aged persons had clonal expansions within the BV3, -14, -16, and -23 families. Although there was no homology among the eight CDR3 sequences identified in clonal T cells from 8 aged persons, selective pressure on the expanded T cell clones was suggested by the fact that the BV families used by the T cell clones were not proportional to the number of genes in the different BV families.
Asunto(s)
Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD8-positivos/inmunología , Subgrupos de Linfocitos T/inmunología , Adulto , Factores de Edad , Anciano , Secuencia de Aminoácidos , Recuento de Linfocito CD4 , Humanos , Inmunofenotipificación , Antígenos Comunes de Leucocito/metabolismo , Recuento de LinfocitosRESUMEN
We previously demonstrated that when platelets are in motion and in proximity to endothelial cells, they become unresponsive to agonists (Marcus, A.J., L.B. Safier, K.A. Hajjar, H.L. Ullman, N. Islam, M.J. Broekman, and A.M. Eiroa. 1991. J. Clin. Invest. 88:1690-1696). This inhibition is due to an ecto-ADPase on the surface of endothelial cells which metabolizes ADP released from activated platelets, resulting in blockade of the aggregation response. Human umbilical vein endothelial cells (HUVEC) ADPase was biochemically classified as an E-type ATP-diphosphohydrolase. The endothelial ecto-ADPase is herein identified as CD39, a molecule originally characterized as a lymphoid surface antigen. All HUVEC ecto-ADPase activity was immunoprecipitated by monoclonal antibodies to CD39. Surface localization of HUVEC CD39 was established by confocal microscopy and flow cytometric analyses. Transfection of COS cells with human CD39 resulted in both ecto-ADPase activity as well as surface expression of CD39. PCR analyses of cDNA obtained from HUVEC mRNA and recombinant human CD39 revealed products of the same size, and of identical sequence. Northern blot analyses demonstrated that HUVEC express the same sized transcripts for CD39 as MP-1 cells (from which CD39 was originally cloned). We established the role of CD39 as a prime endothelial thromboregulator by demonstrating that CD39-transfected COS cells acquired the ability to inhibit ADP-induced aggregation in platelet-rich plasma. The identification of HUVEC ADPase/CD39 as a constitutively expressed potent inhibitor of platelet reactivity offers new prospects for antithrombotic therapeusis.
Asunto(s)
Adenosina Trifosfatasas , Antígenos CD/farmacología , Apirasa/farmacología , Endotelio Vascular/enzimología , Inhibidores de Agregación Plaquetaria/farmacología , Animales , Anticuerpos Monoclonales/farmacología , Antígenos CD/química , Antígenos CD/genética , Antígenos CD/inmunología , Apirasa/química , Apirasa/inmunología , Células COS , Células Cultivadas , ADN Complementario/análisis , Endotelio Vascular/citología , Activación Enzimática/inmunología , Humanos , Membranas Intracelulares/enzimología , Microsomas/enzimología , Inhibidores de Agregación Plaquetaria/inmunología , Pruebas de Precipitina , ARN Mensajero/análisis , Proteínas Recombinantes/análisis , Transfección , Venas UmbilicalesRESUMEN
Both superantigens (SAG) and many anti-TCR monoclonal antibodies (mAb) have specificity for the V beta region of the TCR encoded by TCRBV genes. For instance the bacterial SAG staphylococcal enterotoxin E (SEE), the retroviral SAG MTV-9 and the mAb OT145 each react with human T cells expressing BV6S7. This BV gene encodes two common alleles. We found that SEE and the mAb preferentially activate T cells expressing BV6S7*1 as opposed to BV6S7*2, but Mtv-9 activates T cells expressing either allele. Thus binding to the TCR differs between the two SAGs. A mutation in the TCR HVR-4 region of BV6S7*1 (G72E), where the two BV6S7 alleles differ, indicated that HVR-4 is a component of the binding site for SEE and for the mAb OT145. BV6S7*2 has a charged E72 which may result in electrostatic repulsion of SEE, as SEE contains a similarly acidic aspartic acid residue at a TCR interaction site (204D).
Asunto(s)
Enterotoxinas/metabolismo , Modelos Moleculares , Receptores de Antígenos de Linfocitos T alfa-beta/metabolismo , Superantígenos/metabolismo , Alelos , Secuencia de Aminoácidos , Sitios de Unión , Calcio/metabolismo , Citometría de Flujo , Técnica del Anticuerpo Fluorescente Indirecta , Humanos , Activación de Linfocitos , Datos de Secuencia Molecular , Reacción en Cadena de la Polimerasa , Unión Proteica , Receptores de Antígenos de Linfocitos T alfa-beta/genética , Transducción de SeñalRESUMEN
Several human TCR BV gene subfamilies, including BV3, BV14, and BV17S1, are single member genes but are overutilized among activated CD4+ synovial T cells in the rheumatoid arthritis (RA). To define the role of these TCR BV genes in the pathogenesis of disease, it is critical to characterize the genomic organization and the allelic variations of these genes. In this study we describe allelic variations of BV17S1 defined by restriction fragment length polymorphism (RFLP), single strand conformation polymorphism (SSCP), and amplification refractory mutation system (ARMS) analyses. A single nucleotide replacement (C/T) results in an amino acid substitution (F/L) in the leader and distinguishes BV17S1*1 from BV17S1*2. This nucleotide substitution was found to create a BsmAI restriction enzyme recognition site in BV17S1*2. Therefore genotypic analyses can be performed either by the SSCP or RFLP method. The analyses of 75 unrelated individuals show that the frequency for allele BV17S1*1 is 52.7% and for allele BV17S1*2 is 47.3%. Both alleles are functionally expressed and are distributed within CD4+/CD8+ T cell subsets. Another point mutation in the CDR2 region of BV17S1, which results in the amino acid replacement of Gln by His, originally identified form a cDNA clone, has now been confirmed as an allele by ARMS analysis using genomic DNA preparations and designated to as BV17S1*3. Screening of this CDR2 related variant among normal populations indicates that this is a rare allele (1 of 75). Although this variant may be of functional significance, the genotypic analysis and functional studies are difficult due to the low frequency of BV17S1*3. In an attempt to define a correlation between BV17S1 allelic usage and susceptibility to RA, the germline distribution of BV17S1 alleles *1 and *2 has been examined in a small number of RA patients and no skewed usage has been identified.
Asunto(s)
Alelos , Amplificación de Genes/genética , Polimorfismo Genético/genética , Polimorfismo de Longitud del Fragmento de Restricción , Polimorfismo Conformacional Retorcido-Simple , Receptores de Antígenos de Linfocitos T alfa-beta/genética , Secuencia de Aminoácidos , Artritis Reumatoide/genética , Secuencia de Bases , Humanos , Datos de Secuencia Molecular , Mutación/genética , Técnicas de Amplificación de Ácido NucleicoRESUMEN
Herpesviral DNA fragments isolated from AIDS-associated Kaposi's sarcoma (KS) tissue (KSHV-DNA) share homology with two lymphotropic oncogenic gamma-herpesviruses, Epstein-Barr virus and Herpesvirus saimiri, and are present in the lesions of more than 95% of HIV and non-HIV-associated forms of KS, AIDS-related body cavity-based lymphomas, and AIDS-related multicentric Castleman's disease. Here we show that BC-1, a KSHV-DNA-positive, body cavity-based lymphoma cell line, produces infective herpesviral particles carrying a linear 270-kb genome that specifically transmits KSHV-DNA to CD19+ B cells. Transmission of KSHV-DNA is dependent upon a biologically active, replicating virus, since it is blocked by UV irradiation and foscarnet, an inhibitor of viral DNA-polymerase. This study represents the first isolation and transmission of the human herpesvirus-8/KS-associated herpesvirus.
Asunto(s)
Síndrome de Inmunodeficiencia Adquirida/complicaciones , Linfocitos B/virología , Herpesviridae/clasificación , Herpesviridae/fisiología , Sarcoma de Kaposi/virología , Southern Blotting , Línea Celular , Sondas de ADN , ADN Viral/análisis , Sangre Fetal , Genoma Viral , Herpesviridae/aislamiento & purificación , Herpesvirus Saimiriino 2/clasificación , Herpesvirus Humano 4/clasificación , Humanos , Reacción en Cadena de la Polimerasa , Sarcoma de Kaposi/etiologíaRESUMEN
Human immunodeficiency virus-1 (HIV-1) replicates more efficiently in T cells expressing T-cell receptors using certain V beta genes, V beta 12 in particular. This V beta specificity was consistent with an HIV-1-associated superantigen. In addition, T cell-depleted peripheral blood mononuclear cells from HIV-positive donors potently stimulated V beta 12 cell lines to proliferate in culture, but not control B beta 6.7a cell lines, thus indicating the presence of a V beta-selective mitogen. The targeted V beta subsets were not deleted. It was therefore possible that these subsets might represent a viral reservoir in vivo. Viral load was assessed by quantitative polymerase chain reaction (with HIV-1 gag primers) and with an infectivity assay to measure competent virus. It was shown that the tiny V beta 12 subset (1-2% of T cells) has a higher viral load than other V beta subsets in about 65% of infected individuals. Selective HIV-1 replication in V beta 12 cells was also observed 6-9 days after in vitro infection of peripheral blood T cells from several normal HIV-1-negative donors. In summary, a superantigen-like activity appears to promote V beta-selective HIV-1 replication in vitro and in vivo in patients infected with HIV-1. New therapeutic approaches are suggested based on these findings.
Asunto(s)
Linfocitos T CD4-Positivos/virología , VIH-1/inmunología , Superantígenos/inmunología , Subgrupos de Linfocitos T/virología , Síndrome de Inmunodeficiencia Adquirida/terapia , Síndrome de Inmunodeficiencia Adquirida/virología , Humanos , Receptores de Antígenos de Linfocitos T alfa-beta/genética , Replicación ViralRESUMEN
HIV-1 replicates more efficiently in cultured IL-2-dependent CD4 T cells expressing V beta 12 T cell receptors (TCRs) rather than other TCRs (Laurence et al., 1992). A viral reservoir is frequently established in V beta 12 T cells in HIV-1-infected patients. Here we show that cytomegalovirus (CMV) is responsible for V beta 12-selective HIV-1 replication that is indistinguishable from the effect of known superantigens (SAGs). This effect is dependent on direct contact of T cells with CMV-infected monocytes. CMV infection, but not ie1 or ie2 transfection, reproduces this effect in a monocytoid cell line (U937). In HIV-infected patients, the presence of CMV antibodies correlates with an HIV-1 viral load preferentially skewed to the V beta 12 subset. Together, these data suggest that a CMV gene product is responsible for a SAG-driven V beta 12-selective HIV-1 reservoir in vivo.
Asunto(s)
Citomegalovirus/fisiología , VIH-1/fisiología , Herpesviridae/inmunología , Monocitos/virología , Superantígenos/inmunología , Síndrome de Inmunodeficiencia Adquirida/inmunología , Animales , Antígenos Virales/inmunología , Secuencia de Bases , Linfocitos T CD4-Positivos/ultraestructura , Linfocitos T CD4-Positivos/virología , Células Cultivadas/virología , Cricetinae , Infecciones por Citomegalovirus/inmunología , Humanos , Datos de Secuencia Molecular , Replicación ViralRESUMEN
Both environmental and genetic factors combine to shape the TCR repertoire as measured by V gene usage. These factors may result in dramatic shifts in normal subjects, which cannot be discounted when studies are performed in patients with disease. Future studies need to explore further examples of genetic and environmental factors that shape the TCR repertoire to understand the full extent of variation in a normal population and the mechanisms involved. Some of these mechanisms may also apply to TCRG, TCRD, and immunoglobulin loci. Certainly variations in the efficiency of V(D)J rearrangement could affect any rearranging multigene locus. Eventually such studies will lead to better designed clinical studies of the repertoire in disease, through the selection of control populations matched for environmental exposure and genetic background. In this respect, family studies will be most useful.