RESUMEN
Combination antiretroviral therapy can suppress human immunodeficiency virus (HIV) infection but cannot completely eradicate the virus. A major obstacle in the quest for a cure is the difficulty in targeting and measuring latently infected cells. To date, a single person seems to have been cured of HIV. Hematopoietic stem cell transplantation (HSCT) preceded this cancer patient's long-term sustained HIV remission, but researchers have been unable to replicate this cure, and the mechanisms that led to HIV remission remain to be established. In February 2014, the National Institute of Allergy and Infectious Diseases sponsored a workshop that provided a venue for in-depth discussion of whether HSCT could be exploited to cure HIV in cancer patients requiring such procedures. Participants also discussed how HSCT might be applied to a broader community of HIV-infected persons in whom the risks of HSCT currently outweigh the likelihood and benefits of HIV cure.
Asunto(s)
Infecciones por VIH/terapia , Trasplante de Células Madre Hematopoyéticas/métodos , Investigación Biomédica/tendencias , HumanosRESUMEN
Numerous autoimmune and inflammatory disorders stem from the dysregulation of hematopoietic cell activation. The activity of inositol lipid and protein tyrosine phosphatases, and the receptors that recruit them, is critical for prevention of these disorders. Balanced signaling by inhibitory and activating receptors is now recognized to be an important factor in tuning cell function and inflammatory potential. In this review, we provide an overview of current knowledge of membrane proximal events in signaling by inhibitory/regulatory receptors focusing on structural and functional characteristics of receptors and their effectors Src homology 2 (SH2) domain-containing tyrosine phosphatase 1 and SH2 domain-containing inositol 5-phosphatase-1. We review use of new strategies to identify novel regulatory receptors and effectors. Finally, we discuss complementary actions of paired inhibitory and activating receptors, using Fc gammaRIIA and Fc gammaRIIB regulation human basophil activation as a prototype.
Asunto(s)
Basófilos/metabolismo , Retroalimentación Fisiológica/inmunología , Receptores de IgG/metabolismo , Transducción de Señal/inmunología , Animales , Enfermedades Autoinmunes/etiología , Enfermedades Autoinmunes/metabolismo , Basófilos/inmunología , Sistema Hematopoyético/citología , Sistema Hematopoyético/inmunología , Sistema Hematopoyético/metabolismo , Humanos , Inositol Polifosfato 5-Fosfatasas , Monoéster Fosfórico Hidrolasas/inmunología , Monoéster Fosfórico Hidrolasas/metabolismo , Unión Proteica , Proteínas Tirosina Fosfatasas/metabolismo , Agregación de Receptores/inmunología , Receptores de IgG/química , Receptores de IgG/inmunología , Relación Estructura-Actividad , Dominios Homologos srcRESUMEN
How self tolerance is maintained during B cell development in the bone marrow has been a focal area of study in immunology. Receptor editing, anergy and clonal deletion all play important roles in the regulation of autoimmunity in the immature population. The mechanisms of tolerance induction in the periphery, however, are less well characterized. Overexpression of the apoptosis inhibitor Bcl-2 rescues autoreactive B cells from deletion and can contribute to the development of autoimmune disease in certain genetic backgrounds. Using a peptide-induced autoimmunity model, we recently identified a peripheral tolerance checkpoint in antigen-activated B cells that have undergone class switching and somatic hypermutation. At this checkpoint, receptor editing, induced by antigen engagement, dampened the autoantibody response. In this study, we show that receptor editing fails to be induced in antigen-activated DNA-reactive B cells that overexpress Bcl-2 (Bcl-2 Tg). The failure to induce RAG and receptor editing is likely due, at least partially, to the lack of self antigen. First, the levels of circulating DNA and of apoptotic bodies in the spleen of Bcl-2 Tg mice are significantly lower than in control mice. Second, in Bcl-2 Tg mice, RAG can be induced in a population of antigen-activated B cells by providing exogenous soluble antigen. These data suggest that, in addition to its anti-apoptotic activity, Bcl-2 may indirectly inhibit tolerance induction in B cells acquiring anti-nuclear antigen reactivity after peripheral activation by limiting the availability of self antigen.
Asunto(s)
Apoptosis/inmunología , Linfocitos B/inmunología , ADN/inmunología , Tolerancia Inmunológica/genética , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Animales , Anticuerpos Antinucleares/sangre , Anticuerpos Antinucleares/inmunología , Apoptosis/genética , Autoantígenos/inmunología , Autoinmunidad/genética , Autoinmunidad/inmunología , ADN/sangre , Proteínas de Unión al ADN/antagonistas & inhibidores , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/inmunología , Epítopos/inmunología , Femenino , Regulación de la Expresión Génica/genética , Regulación de la Expresión Génica/inmunología , Inmunización , Memoria Inmunológica/genética , Ratones , Ratones Endogámicos BALB C , Ratones Transgénicos , Imitación Molecular/inmunología , Péptidos/síntesis química , Péptidos/inmunología , Proteínas Proto-Oncogénicas c-bcl-2/genética , Bazo/inmunologíaRESUMEN
Biotoxin activity assays typically involve multistep sample preparation, multicomponent reactions, multistep analysis, or a combination thereof. We report a single-step, real-time ricin activity assay that requires little or no sample preparation and employs direct analysis in real time mass spectrometry. The release of adenine from the inhomogeneous substrate herring sperm DNA by ricin was determined to be 53 +/- 2 pmol adenine per picomole of ricin per hour. This procedure can be readily adapted to any enzyme for which a reactant or product of low molecular weight (up to approximately 600) can be identified.
Asunto(s)
Adenina/análisis , Espectrometría de Masas/métodos , Ricina/metabolismo , ADN/metabolismo , HumanosRESUMEN
B cells and autoimmunity: cells of the immune system have the capacity to recognize/neutralize a myriad array of disease-causing pathogens, while simultaneously minimizing damage to self tissue. Obvious breakdowns in this ability to distinguish between self and non-self are evident in multiple forms of autoimmune disease, where B and T cells mount damaging attacks on cells and organs. B cells may directly damage tissue by producing pathogenic antibodies that bind self antigen, fix complement or form immune complexes. Recent evidence also suggests B cells indirectly induce autoimmunity by concentrating low avidity self antigen through the B cell receptor and presenting self-peptides to autoreactive T cells. B cells may also initiate autoimmunity when provided sufficient help from autoreactive T cells that have escaped deletion in the thymus. Here, we will review the role of anergy in maintenance of tolerance and how alterations in the normal balance of positive and negative signals may contribute to the development of autoimmune disease in mouse models and humans.
Asunto(s)
Antígenos CD/inmunología , Autoinmunidad , Linfocitos B/inmunología , Receptores de Antígenos de Linfocitos B/inmunología , Autotolerancia , Receptores Toll-Like/metabolismo , Animales , Antígenos CD/metabolismo , Linfocitos B/metabolismo , Humanos , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Activación de Linfocitos , Receptores de Antígenos de Linfocitos B/metabolismo , Transducción de Señal , Linfocitos T/inmunologíaRESUMEN
The products formed from the degradation of the blister agent sulfur mustard [bis(2-chloroethyl) sulfide] on concrete were identified using gas chromatography with mass spectrometry detection (GC/MSD), (1)H NMR, 2D (1)H-(13)C NMR and (13)C solid state magic angle spinning (SSMAS) NMR. In situ and extraction experiments were performed. Sulfur mustard was detected in the in situ (13)C SSMAS samples for 12 weeks, whereas less than 5% of the sulfur mustard was detected in extracts from the concrete monoliths after 8 days. Sulfonium ions and (2-chloroethylthio)ethyl ether (T) were observed on the in situ samples after a period of 12 weeks, whereas vinyl species and bis(2-chloroethyl) sulfoxide were observed in the extracts of the concrete monoliths within 24h. The differences between the extraction and the SSMAS data indicated that the sulfur mustard existed in the concrete in a non-extractable form prior to its degradation. Extraction methods alone were not sufficient to identify the products; methods to identify the presence of non-extractable degradation products were also required.
Asunto(s)
Biodegradación Ambiental , Gas Mostaza/metabolismo , Materiales de Construcción , Cromatografía de Gases y Espectrometría de Masas , Espectroscopía de Resonancia Magnética , Compuestos de Sulfonio/análisisRESUMEN
The difficulty in characterizing antigen-specific B cells that arise in the native B cell repertoire has been a formidable obstacle to understanding both protective and pathogenic antibody responses. We have developed a tetramer-based technique for identifying antigen-specific B cells. Biotin-labeled antigen is made tetrameric by interaction with streptavidin. The enhanced avidity of this antigenic compound for the B cell membrane permits the visualization, characterization and isolation of antigen-specific B cells.
Asunto(s)
Antígenos , Subgrupos de Linfocitos B/inmunología , Animales , Antígenos/química , Antígenos CD/química , Antígenos CD/genética , Antígenos CD/metabolismo , Biotina , Antígenos CD79 , Membrana Celular/inmunología , Femenino , Citometría de Flujo , Expresión Génica , Inmunización , Técnicas In Vitro , Ratones , Ratones Endogámicos BALB C , Reacción en Cadena de la Polimerasa , Estructura Cuaternaria de Proteína , Bazo/citología , Bazo/inmunología , EstreptavidinaRESUMEN
Receptor editing or secondary Ig gene rearrangement occurs in immature, autoreactive B cells to maintain self-tolerance. Here we show that nonspontaneously autoimmune mice immunized with a peptide mimetope of DNA develop peptide- and DNA-reactive antibodies. Antigen-specific B cells display a follicular B cell phenotype. As these cells move into the memory compartment, many express RAG protein and acquire expression of both kappa and lambda light chains. Thus, this study provides evidence for receptor editing occurring in a mature, antigen-activated B cell population. Because the receptor editing observed here occurred in an autoreactive response to antigen, it may function to maintain peripheral tolerance.
Asunto(s)
Linfocitos B/inmunología , Tolerancia Inmunológica/inmunología , Animales , Células de la Médula Ósea/inmunología , Proteínas de Unión al ADN/deficiencia , Proteínas de Unión al ADN/inmunología , Citometría de Flujo , Proteínas Fluorescentes Verdes/genética , Cadenas Ligeras de Inmunoglobulina/genética , Cadenas lambda de Inmunoglobulina/genética , Ratones , Ratones Endogámicos BALB C , Ratones Noqueados , Ratones Transgénicos , Fenotipo , Reacción en Cadena de la Polimerasa , Bazo/inmunologíaRESUMEN
The solution structure of an 11-mer DNA duplex, d(CGGTCA*CGAGG) x d(CCTCGTGACCG), containing a 10R adduct at dA* that corresponds to the cis addition of the N(6)-amino group of dA(6) to (+)-(9S,10R)-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene was studied by 2D NMR methods. The NOESY cross-peak patterns indicate that the hydrocarbon is intercalated on the 5'-side of the modified base. This observation is the same as that observed for other oligonucleotides containing (10R)-dA adducts but opposite to that observed for the corresponding (10S)-dA adducts which are intercalated on the 3'-side of the modified base. The hydrocarbon is intercalated from the major groove without significant disruption of either the anti glycosidic torsion angle of the modified residue or the base pairing of the modified residue with the complementary residue on the opposite strand. The ensemble of 10 structures determined exhibits relatively small variations (6-15 degrees) in the characteristic hydrocarbon-base dihedral angles (alpha' and beta') as well as the glycosidic torsion angle chi. These angles are similar to those in a previously determined cis-opened benzo[a]pyrene diol epoxide-(10R)-dA adduct structure. Comparison of the present structure with the cis-opened diol epoxide adduct suggests that the absence of the 7- and 8-hydroxyl groups results in more efficient stacking of the aromatic moiety with the flanking base pairs and deeper insertion of the hydrocarbon into the helix. Relative to normal B-DNA, the duplex containing the present tetrahydroepoxide adduct is unwound at the lesion site, whereas the diol epoxide adduct structure is more tightly wound than normal B-DNA. Buckling of the adducted base pair as well as the C(5)-G(18) base pair that lies immediately above the hydrocarbon is much less severe in the present adducted structure than its cis-opened diol epoxide counterpart.