RESUMO
Magnetic porous metal-organic framework nanocomposite was obtained by an easy, efficient, and environmentally friendly fabrication method. The material consists in magnetic spinel iron oxide nanoparticles incorporated in an iron(III) carboxylate framework. The magnetic composite was fabricated by a multistep mechanochemical approach. In the first step, iron oxide nanoparticles were obtained via ball milling inducing mechanochemical reaction between iron chlorides and NaOH using NaCl as dispersing agent. Magnetic nanoparticles (MNs) were functionalized by neat grinding with benzene-1,3,5-tricarboxylic acid (1, 3, 5 BTC) and were then subjected to liquid assisted milling using hydrated FeCl3, water, and ethanol to obtain a magnetic framework composite (MFC) consisting of iron oxide nanoparticles encapsulated in a MOF matrix. We report, for the first time, the applicability of the grinding method to obtain a magnetic composite of metal-organic frameworks. The synthesized material exhibits magnetic characteristics and high porosity, and it has been tested as carrier for targeted drug delivery studying loading and release of a model drug (doxorubicin). Developed systems can associate therapeutics and diagnostics properties with possible relevant impact for theranostic and personalized patient treatment. Furthermore, the material properties make them excellent candidates for several other applications such as catalysis, sensing, and selective sequestration processes.
RESUMO
The cell surface expression of alpha:beta heterodimer was studied using WT31 monoclonal antibody, in peripheral blood lymphocytes (PBL) from a patient who developed a prolonged immunodeficiency after allogeneic bone marrow transplantation. This patient, grafted for chronic myelogenous leukemia, received T cell depleted bone marrow from her HLA, A, B, D matched sibling. The late occurrence of opportunistic infection, led us to analyze the phenotype of patient PBL. 70% of PBL were CD3+ and 29% WT31+, indicating that the majority of CD3+ PBL did not express the alpha:beta heterodimer. Transcription of the genes encoding the alpha, beta, and gamma chains was assessed in cell lines derived from PBL, by Northern blot analysis. We showed that the CD3+ WT31- subset expressed a truncated, beta mRNA (1.0 kb) and also truncated alpha transcript (1.4 kb). To determine the CD3-associated structure on CD3+ WT31- cell line, immunoprecipitation assays were performed using monoclonal anti-CD3 and an hetero antiserum against gamma peptides. These CD3+ WT31- cells expressed a disulfide linked dimer, composed of products of gamma gene (37 kD, 40 kD) and of undefined delta chain (45 kD). Functional analyses were performed in PBL before and after sorting with WT31 and anti-CD3 antibody. These circulating CD3+ WT31- cells were unable to proliferate when triggered with anti-T3 beads and they seemed to mediate a suppressor activity on CD3+ WT31+ cells.
Assuntos
Antígenos de Diferenciação de Linfócitos T , Transplante de Medula Óssea , Síndromes de Imunodeficiência/imunologia , Receptores de Antígenos de Linfócitos T/análise , Linfócitos T/classificação , Adulto , Anticorpos Monoclonais , Antígenos de Diferenciação de Linfócitos T/análise , Feminino , Humanos , Síndromes de Imunodeficiência/genética , Síndromes de Imunodeficiência/metabolismo , Fenótipo , RNA Mensageiro/isolamento & purificação , Linfócitos T/imunologia , Linfócitos T/metabolismo , Transcrição GênicaRESUMO
During early embryogenesis of both vertebrates and invertebrates, antagonism between bone morphogenetic proteins (BMPs) and several unrelated secreted factors including Chordin (Chd) is a general mechanism by which the dorso-ventral axis is established. High affinity binding of Chd sequesters the BMP ligands in the extracellular space, preventing interactions with their membrane receptors. Another level of regulation consists in processing of vertebrate Chd or its Drosophila counterpart Sog by astacine metalloproteases like Xolloid-BMP-1/Tolloid, respectively, which releases an active BMP. Recently, it was shown that cleavage of Sog by Tolloid could generate novel BMP inhibitory activity and that sog is also capable of stimulation of BMP activity in a tolloid-dependant way. Activity and/or cleavage of Chd/Sog are influenced by other secreted factors like twisted gastrulation. In this study, we have cloned cDNAs of the human chordin gene (CHRD) and characterized alternative splice variants that code for C-truncated forms of the protein. We have found that CHRD is expressed in fetal as well as in adult tissues with relatively high levels in liver, cerebellum and female genital tract, suggesting functions in late embryogenesis and adult physiology. We also show that spliced variants are present with specific patterns in various tissues. When tested in an axis-duplication assay in Xenopus, we find that these variants can antagonize BMP activity. Altogether, these results suggest that, in addition to processing by metalloproteases, alternative splicing (AS) is another mechanism by which sub-products of CHRD can be generated to influence BMP activity in different developmental and physiological situations.
Assuntos
Processamento Alternativo , Proteínas Morfogenéticas Ósseas/antagonistas & inibidores , Expressão Gênica , Glicoproteínas , Peptídeos e Proteínas de Sinalização Intercelular , Proteínas/genética , Proteínas/fisiologia , Sequência de Aminoácidos , Animais , Sequência de Bases , Padronização Corporal , Proteínas Morfogenéticas Ósseas/metabolismo , Mapeamento Cromossômico , Clonagem Molecular , DNA Complementar , Embrião de Mamíferos/metabolismo , Embrião não Mamífero , Desenvolvimento Embrionário , Feto/metabolismo , Perfilação da Expressão Gênica , Humanos , Dados de Sequência Molecular , Proteínas/química , XenopusRESUMO
Concurrent activation of BCL2 and MYC usually occurs in B cell non-Hodgkin lymphoma (B-NHL) by translocation of both oncogenes to both immunoglobulin heavy chain (IGH) alleles: this abrogates immunoglobulin synthesis. We have studied three B-NHL cell lines (DoHH2, VAL and ROS 50) and show that concurrent activation of BCL2 and MYC may follow translocation of both oncogenes to the same IGH allele. Conventional cytogenetics of DoHH2 suggested the presence of a t(14;18)(q32;q21) translocation. However, fluorescent in situ hybridization (FISH) studies using whole chromosome paints, alpha satellite probes and flow-sorted chromosomes as probes revealed an unexpected complexity of rearrangements involving chromosomes 8, 14 and 18, namely t(8;14;18)(q24;q32;q21). DNA blot and previous PCR analysis confirmed the juxtaposition of BCL2 major breakpoint region (mbr) with IGJH6, but also demonstrated a rearrangement within the first exon of MYC. The centromeric (5') MYC rearranged fragment comigrated with the BCL2-JH6 rearranged fragment in BamHI, EcoRI and Bg/II restriction digests. The der(8)t(8;14;18) therefore comprised 5' MYC (exon I)-Sgamma4-JH6-BCL2 mbr. Similar rearrangements were observed in both ROS 50 and VAL cell lines which contained two and three copies of the der(8)t(8;14;18) respectively. Quantitative flow cytometry for BCL2 and MYC expression showed abundant expression of both proteins in all three lines. These data indicate the der(14)t(14;18)(q32;q21) may itself be the target for any second translocation. The presence of the intact BCL2-JH fusion gene on the der(8)t(8;14;18) allowed concurrent activation of both BCL2 and MYC with no loss of immunoglobulin expression.
Assuntos
Regulação Neoplásica da Expressão Gênica , Genes myc , Cadeias Pesadas de Imunoglobulinas/genética , Linfoma de Células B/genética , Proteínas Proto-Oncogênicas/genética , Proto-Oncogenes/genética , Translocação Genética , Idoso , Alelos , Mapeamento Cromossômico , Cromossomos Humanos Par 14 , Cromossomos Humanos Par 18 , Cromossomos Humanos Par 8 , Feminino , Humanos , Hibridização in Situ Fluorescente , Linfoma de Células B/imunologia , Masculino , Pessoa de Meia-Idade , Proteínas Proto-Oncogênicas c-bcl-2 , Células Tumorais CultivadasRESUMO
A cDNA library prepared from a human fetal liver of the first trimester of gestation was screened with Ig C mu, C gamma, C kappa and C lambda probes. Ten heavy chain clones were isolated and characterized by restriction mapping and partial sequencing. The absence of Ig light chain clone and the presence of pre-B-specific lambda-like transcripts suggest that the immune compartment of this cDNA library was mostly derived from pre-B cells. Three transcripts of mu, gamma 2 and gamma 4 isotypes contained a V-D-J-C region with an open reading frame and used members of the VHIV, VHIII and VHI families, respectively. Seven clones were derived from sterile transcripts, one C mu and six C gamma. In addition to C mu exons, the sterile mu transcript contained the 5' flanking germline region. By contrast, the gamma sterile transcripts used a 5' sequence that was spliced from the I gamma 1 region onto the first C gamma 1 exon. In addition several of these transcripts were derived from alternative splicing. The simultaneous expression of both sterile and functional gamma transcripts suggests that the switch mechanism operates in normal fetal liver very early in ontogeny.
Assuntos
Variação Antigênica/imunologia , Cadeias Pesadas de Imunoglobulinas/imunologia , Isotipos de Imunoglobulinas/imunologia , Fígado/imunologia , Variação Antigênica/genética , Sequência de Bases , Clonagem Molecular , DNA , Sondas de DNA , Biblioteca Gênica , Humanos , Immunoblotting , Regiões Constantes de Imunoglobulina/genética , Cadeias Pesadas de Imunoglobulinas/genética , Isotipos de Imunoglobulinas/genética , Fígado/embriologia , Dados de Sequência Molecular , Splicing de RNA , Mapeamento por RestriçãoRESUMO
The Burkitt's lymphoma cell line Ly66 produces a short mu chain which lacks 4 kDa in apparent molecular mass. Study of the corresponding messenger RNA showed it to be 0.3 kb shorter than normal mu transcripts. The cDNA sequence of the mu transcripts began by a short VH region consisting of the first one-third of a VHIV subgroup gene segment. It was followed by a normal mu constant region. This VH region coded for 38 amino acids, thus differing from two truncated VHIV regions previously reported in other Burkitt's lymphoma cell lines, which were interrupted at codon +26 by an alternate splicing event. In addition, the Ly66 variable sequence bore several point mutations and contained two potential N-glycosylation sites.
Assuntos
Linfoma de Burkitt/genética , Cadeias Pesadas de Imunoglobulinas/genética , Região Variável de Imunoglobulina/genética , Sequência de Aminoácidos , Sequência de Bases , Northern Blotting , Southern Blotting , Clonagem Molecular , Glicosilação , Humanos , Regiões Constantes de Imunoglobulina/genética , Dados de Sequência Molecular , Peso Molecular , Splicing de RNA , Células Tumorais CultivadasRESUMO
A patient (BW) was studied with Mu heavy chain disease (mu HCD) in whom a leukemic B-cell clone secreted a shortened monoclonal mu chain without associated light chain. The cells did, however, produce a normal-sized kappa light chain that was detected as urinary Bence-Jones protein. The cytoplasmic and secreted monomeric mu chain had an approximate mol. wt of 58,000. Radiochemical sequence analysis of the biosynthetically labelled mu chain revealed a protein that lacked the entire variable region. The sequence initiated at amino acid position 5 within the first constant region domain (CH1) of C mu. The primary in vitro translation product, the cytoplasmic and secreted proteins were all similarly truncated, thereby excluding extensive postsynthetic degradation. The mu RNA, that directed the synthesis of the truncated mu protein, was about 350 bp smaller than the normal mu RNA. Furthermore, by primer extension analysis it was possible to localize this deletion in the mu RNA to a region 5' of CH1. Thus, a defect at the level of Ig gene structure/assembly that deletes coding information or results in aberrant RNA processing must be responsible for the truncated mu HCD protein BW.
Assuntos
Doença das Cadeias Pesadas/genética , Cadeias mu de Imunoglobulina , Sequência de Aminoácidos , Proteína de Bence Jones/urina , Eletroforese em Gel de Poliacrilamida , Feminino , Humanos , Imunoeletroforese , Cadeias mu de Imunoglobulina/biossíntese , Cadeias mu de Imunoglobulina/genética , Biossíntese de Proteínas , RNA Mensageiro/análiseRESUMO
Oligo(ethylene glycol)-based (OEG) hydrogel samples of varying cross-link densities and degrees of swelling were characterized through dynamic nanoindentation testing. Experiments were performed using a non-standard nanoindentation method, which was validated on a standard polystyrene sample. This method maximizes the capability of the instrument to measure the stiffness and damping of highly compliant, viscoelastic materials. Experiments were performed over the frequency range of 1 to 50 Hz, using a 1mm diameter flat punch indenter. A hydration method was adopted to avoid sample dehydration during testing. Values of storage modulus (E') ranged from 3.5 to 8.9 MPa for the different OEG-hydrogel samples investigated. Samples with higher OEG concentrations showed greater scatter in the modulus measurements and it is attributed to inhomogeneities in these materials. The (E') values did not show a strong variation over frequency for any of the samples. Values of loss modulus (E") were two orders of magnitude lower than the storage modulus, resulting in very low values of loss factor (E"/E'<0.1). These are characteristics of strong gels, which present negligible viscous properties.
Assuntos
Hidrogéis , Teste de Materiais/métodos , Fenômenos Mecânicos , Nanotecnologia/métodos , Polietilenoglicóis/química , Elasticidade , Poliestirenos/química , ViscosidadeRESUMO
Three patients presented with renal or more diffuse tissue deposits of a nonamyloid material reactive with anti-kappa antibody by immunofluorescence. All patients had progressive renal failure with the nephrotic syndrome and extensive tubular basement membrane deposits. Glomerular lesions were conspicuous but heterogeneous. One patient also had hepatic deposits with peliosis at histopathologic examination. An underlying lymphoplasmacytic disorder was found in all patients: multiple myeloma in one, pleomorphic lymphoplasmacytic malignancy analogous to Waldenström's macroglobulinemia in one and bone marrow monoclonal plasmacytosis without overt myeloma in one. Biosynthesis experiments in two cases showed production of abnormal kappa chains which were not detected in appreciable amounts in serum and urine. These light chains had an aberrant size (abnormally short or large), their apparent molecular weight was larger in secretion than in cytoplasmic extracts (suggesting their glycosylation) and they were secreted as polymers. These results suggest a causal relationship between production of abnormal light chains and tissue deposition.
Assuntos
Cadeias Leves de Imunoglobulina/biossíntese , Cadeias kappa de Imunoglobulina/biossíntese , Paraproteinemias/imunologia , Plasmocitoma/imunologia , Macroglobulinemia de Waldenstrom/imunologia , Adulto , Membrana Basal/imunologia , Medula Óssea/imunologia , Feminino , Humanos , Cadeias kappa de Imunoglobulina/isolamento & purificação , Glomérulos Renais/imunologia , Túbulos Renais/imunologia , Fígado/imunologia , Masculino , Pessoa de Meia-Idade , Mieloma Múltiplo/imunologia , Paraproteinemias/diagnósticoRESUMO
A quantitative assay is necessary to differentiate between low and high Cytomegalovirus load in the blood, a high load frequently being correlated with clinical disease. A new method for the quantitative determination of viral DNA (HCMV-hybrid-capture) was compared with antigenemia and PCR. Hybrid-capture proved to be a simple and rapid method for the quantitative determination of viral load in the blood. It is less sensitive than PCR and antigenemia, but seems to correlate with clinical symptoms as well as the antigenemia test and better than non quantitative PCR.
Assuntos
Infecções por Citomegalovirus/diagnóstico , Citomegalovirus/isolamento & purificação , DNA Viral/sangue , Kit de Reagentes para Diagnóstico , Síndrome da Imunodeficiência Adquirida/imunologia , Síndrome da Imunodeficiência Adquirida/virologia , Anticorpos Antivirais , Antígenos Virais/sangue , Citomegalovirus/genética , Citomegalovirus/imunologia , Humanos , Imunoensaio/métodos , Hospedeiro Imunocomprometido , Transplante de Órgãos , Reação em Cadeia da Polimerase , Valor Preditivo dos Testes , Sondas RNA , Sensibilidade e Especificidade , Carga ViralRESUMO
Ig alpha and Ig beta are two glycosylated transmembrane proteins of the Ig superfamily that are encoded by the B cell-specific genes mb-1 and B29, respectively. Ig alpha/Ig beta heterodimers may associate with the mu/surrogate light chains (psi LC) complex and with membrane Immunoglobulins on the surface of pre-B and B cells, respectively. They play a crucial role in the signal transduction that follows pre-B and B cell receptor cross-linking. Previous works have shown that mb-1 and B29 transcripts are expressed in normal mouse and human pro-B cells. However, little is known about the expression of Ig alpha and Ig beta molecules in pro-B cells. To address this issue we first analysed the expression of the Ig alpha and Ig beta molecules in the RS4; 11 and Nalm16 human pro-B cell lines using specific monoclonal antibodies. We found that both cell lines expressed Ig alpha and Ig beta but this expression was limited to the cytoplasm compartment. Three forms (44, 40 and 36 kDa) of the Ig alpha molecule and a single form (36 kDa) of the Ig beta molecule were detected in these lines. The heterogeneity of the Ig alpha molecule was partly related to the presence of a truncated Ig alpha protein which is likely the product of a short mb-1 transcript expressed in these cell lines. This short transcript is generated by alternative splicing of the mb1 mRNA with loss of exon 2. Ig alpha heterogeneity was also related to the expression of different glycosylated forms of the Ig alpha molecule. Only a minor fraction of the Ig alpha and Ig beta molecules associate with each other to form Ig alpha/Ig beta heterodimers and Ig beta homodimers. In these pro-B cell lines Ig alpha and Ig beta were found to associate with the lyn tyrosine kinase, suggesting that they may play some functional role at this B cell differentiation stage. Transfection of muHC gene in the Nalm16 cells results in the assembly of the pre-B receptor and in its expression on the cell surface. The level of surface expression of the pre-B receptor was found to correlate with the level of muHC and psi LC synthesis and with the level of association of the different components of the pre-B receptor with each other. Analysis of the 697 and Nalm6 pre-B cells and of the Ramos B cells indicated that heterogeneity of Ig alpha and Ig beta increases as a function of B cell differentiation.
Assuntos
Antígenos CD/biossíntese , Cadeias Leves de Imunoglobulina/biossíntese , Leucemia-Linfoma Linfoblástico de Células Precursoras B/imunologia , Receptores de Antígenos de Linfócitos B/biossíntese , Antígenos CD79 , Humanos , Células Tumorais CultivadasRESUMO
The authors evaluated the advantages obtained utilizing FNAB with ultrasound in the needle aspiration of breast cysts. Echography can guide the aspiration up to its end in an effective and localized way. Cytologic examination of the cystic fluid confirmed the benign nature of the cyst. The association of needle aspiration and guided echography was related to a low number of relapses (19.8%). Among these relapses some risk factors have been found as well as a correlation between cystic fluid cytologic examination and relapses incidence has been determined.
Assuntos
Biópsia por Agulha , Doença da Mama Fibrocística/patologia , Adolescente , Adulto , Mama/patologia , Feminino , Doença da Mama Fibrocística/diagnóstico por imagem , Doença da Mama Fibrocística/terapia , Humanos , Pessoa de Meia-Idade , Recidiva , UltrassonografiaRESUMO
Nipple discharge, a rare clinical sign, is more frequently determined by benign breast diseases, but it can be associated to breast cancer; for this reason such clinical sign shouldn't be ignored. Cytologic examination together with breast examination and thermography are the correct oncologic approach for nipple discharge, because such way it is possible to select the patients for whom mammography or galactography are recommended as well as and breast biopsy depending on the galactographic data.
Assuntos
Doenças Mamárias/diagnóstico , Neoplasias da Mama/diagnóstico , Mamilos/metabolismo , Adulto , Protocolos Clínicos , Citodiagnóstico/métodos , Feminino , Humanos , Pessoa de Meia-IdadeRESUMO
The Authors demonstrated the presence of tumour cells by an in vitro culture of the cells from the pellet of a postoperative saccate effusion, when no tumor cells were evident by the cytologic examination of the effusion. The ultrastructural features and the immunocytochemical characteristics of the cell line were analyzed and these data confirmed its malignant nature. It allowed a firm diagnosis, a correct therapy and prognosis.
Assuntos
Neoplasias da Mama/patologia , Exsudatos e Transudatos/citologia , Linfa/citologia , Complicações Pós-Operatórias/patologia , Células Tumorais Cultivadas/patologia , Feminino , Humanos , Pessoa de Meia-IdadeRESUMO
Different collagen types (I, III, IV, V) were identified in breast carcinoma desmoplastic tissue by ultrastructural analysis and immunoelectronmicroscopy. Type V collagen is present as a 12 nm. fibril in the stroma, either adjacent to the basement membrane or concentrated around the thicker fibers. Myofibroblasts, fibroblasts and tumor cells can be its major producers. Its possible function as a bridge between different collagens can be utilized, with different finality, by the same cells that have produced it. Furthermore, type V collagen can be involved in tumor invasion of the stroma and in all directional movements of tumor cells, as already demonstrated for other extracellular matrix components.
Assuntos
Neoplasias da Mama/química , Neoplasias da Mama/ultraestrutura , Carcinoma Intraductal não Infiltrante/química , Carcinoma Intraductal não Infiltrante/ultraestrutura , Colágeno/análise , Fibrose , Humanos , Microscopia ImunoeletrônicaRESUMO
Drug allergies are heterogeneous and multifactorial diseases and are always the consequence of an exaggerated immune-mediated reaction. Previously described models of immunologic mechanisms (mainly based on Gell and Combs' classification) cannot fully explain the physiopathology of these diseases; it seems therefore important to identify risk factors. Clinical and biologic tests are helpful diagnostic tools but are limited in their sensitivity and reliability and are certainly not predictive. Epidemiologic data supply information concerning the prevalence of drug hypersensitivity: female gender, concomitant infections (HIV, herpes) and concurrent illnesses (systemic lupus erythematosus) are all significant risk factors. Another host-related factor is the genetic predisposition of patients and is currently under investigation in our laboratory. Most genetic studies concern HLA haplotype association or polymorphism in genes encoding drug-metabolising enzymes. A current study by our group seems to implicate polymorphisms within the promoter of IL-10, a cytokine with anti-inflammatory properties. The chemical properties of the drug and the treatment regimen also influence the development of drug allergies.
Assuntos
Hipersensibilidade a Drogas/epidemiologia , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos , Hipersensibilidade a Drogas/imunologia , Humanos , Prevalência , Fatores de RiscoRESUMO
BACKGROUND: Allergic reactions to beta-lactam antibiotics represent the most frequent cause of immunological drug reactions. OBJECTIVE: This study evaluates the involvement of genetic susceptibility factors in patients with immediate allergic reactions to beta-lactams. We examined 15 single nucleotide polymorphisms (SNP) of genes coding proteins implicated in immunoglobulin (Ig)E synthesis regulation. METHODS: We performed a case-control study involving 44 patients with immediate beta-lactam allergy and 44 control subjects, all matched for sex and atopy. Interleukin (IL)-4, IL-13, IL-4Ralpha, signal transducer and activator of transcription 6 (STAT6), interferon (IFN)-gammaR1, IFN-gammaR2 and FcepsilonRIbeta gene polymorphisms were determined using polymerase chain reaction (PCR) restriction fragment length polymorphism, and IL-21R gene and IL-10 promoter polymorphisms by direct sequencing. RESULTS: Our analysis did not reveal differences in the distribution of the 15 SNPs between allergic patients and controls. However, among atopic subjects, we found two distinct significant associations between immediate beta-lactam allergy in women and the Ile75Val variant of IL-4Ralpha gene (P = 0.012, OR = 5.4, CI: 1.16-27.7), and two linked IL-10 promoter gene polymorphisms, -819C>T and -592 C>A (P = 0.023, OR = 17.5, CI: 1.26-533.07). In contrast, we observed no association in allergic male subjects in the atopic population. Interestingly, the IL-4Ralpha Ile75Val variant could have a paradoxal protective effect in atopic male patients (P = 0.004, OR = 0.07, CI: 0.01-0.66). CONCLUSION: Our findings suggest that polymorphisms in the IL-10 promoter and IL-4Ralpha genes are genetic factors that favour beta-lactam immediate allergies in female patients with atopy.
Assuntos
Hipersensibilidade a Drogas/genética , Predisposição Genética para Doença , Interleucina-10/genética , Subunidade alfa de Receptor de Interleucina-4/genética , Polimorfismo de Nucleotídeo Único , beta-Lactamas , Adolescente , Adulto , Formação de Anticorpos/genética , Formação de Anticorpos/imunologia , Estudos de Casos e Controles , Análise Mutacional de DNA/métodos , Hipersensibilidade a Drogas/imunologia , Feminino , Humanos , Imunoglobulina E/imunologia , Interleucina-10/imunologia , Subunidade alfa de Receptor de Interleucina-4/imunologia , beta-Lactamas/efeitos adversos , beta-Lactamas/imunologia , beta-Lactamas/uso terapêuticoRESUMO
Ordered rearrangement of immunoglobulin genes (heavy chain then kappa and eventually lambda genes) is observed during B lymphocyte ontogeny. Unexpectedly, we found that human mature B cells producing kappa chains and having germ-line lambda genes contain lambda mRNA consisting of an invariant 5' region (herein termed X) and of one of the classical C lambda exons. The X region of these transcripts originates from a unique exon located 5 kb upstream of the J-C lambda 1 gene segment. X-C lambda mRNA expression occurs without somatic DNA rearrangement. The use of the X DNA fragment as a probe allows definition of a family of human genes that comprises at least four members and includes the first exon of the lambda 14.1 gene. The latter is selectively transcribed in pre-B lymphocytes and directs the synthesis of a lambda-like chain. In contrast, the X-C lambda transcripts do not appear to encode a C lambda-related polypeptide in mature B cells. Thus, despite a 73% homology extending far beyond the exon sequences, the X and lambda 14.1 genes are expressed at different stages of B cell development and might serve different functions.
Assuntos
Linfócitos B/metabolismo , Regiões Constantes de Imunoglobulina/genética , Cadeias Leves de Imunoglobulina/biossíntese , Cadeias kappa de Imunoglobulina/genética , Sequência de Aminoácidos , Sequência de Bases , Linhagem Celular , Células Clonais , Éxons/genética , Regulação da Expressão Gênica/imunologia , Rearranjo Gênico de Cadeia Leve de Linfócito B , Humanos , Dados de Sequência Molecular , Família Multigênica , Transcrição Gênica , Células Tumorais CultivadasRESUMO
The proliferating plasma cells of patient COM with nonsecretory myeloma synthesized truncated 42 kDa gamma 1 chains made of a complete constant region but devoid of variable domain. In the absence of light chain expression, the shortened gamma chains were retained intracellularly and were subsequently degraded within 12 h. COM neoplastic plasma cells contained short gamma 1 heavy chain transcripts in which the leader peptide exon was directly joined to the CH1 exon using the regular splice sites. However, study of the productive gamma gene showed that the skipped variable exon was bounded by normal splicing signals and that the adjacent intron organization was not altered. Since this unusual splicing pattern was maintained when COM gamma gene was transfected in murine plasmocytoma cells, exon skipping possibly relates to the modified structure of COM variable region. The latter showed a 2-base pair deletion introducing a translation frameshift in the VH region and a DNA insertion at the VH-DJH junction consisting in a perfect duplication of the first 54 nucleotides of the recombined DJH segment. The lack of light chain production by COM cells was explained by alterations of the variable region of the rearranged kappa gene leading to abnormally spliced transcripts.