Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 41
Filter
1.
QJM ; 112(5): 335-342, 2019 May 01.
Article in English | MEDLINE | ID: mdl-30657990

ABSTRACT

BACKGROUND: Pulmonary arteriovenous malformations (PAVMs) generate a right-to-left shunt. Impaired gas exchange results in hypoxaemia and impaired CO2 clearance. Most patients compensate effectively but some are dyspneic, and these are rarely the most hypoxaemic. AIM: To test degrees of concurrent pathology influencing exercise capacity. DESIGN: Replicate, sequential single centre, prospective studies. METHODS: Cardiopulmonary exercise tests (CPETs) were performed in 26 patients with PAVMs, including individuals with and without known airflow obstruction. To replicate, relationships were tested prospectively in an independent cohort where self-reported exercise capacity evaluated by the Veterans Specific Activity Questionnaire (VSAQ) was used to calculate metabolic equivalents (METs) at peak exercise (n = 71). Additional measurements included oxygen saturation (SpO2), forced expiratory volume in 1 s (FEV1), vital capacity (VC), fractional exhaled nitric oxide (FeNO), haemoglobin and iron indices. RESULTS: By CPET, the peak work rate was only minimally associated with low SpO2 or low arterial oxygen content (calculated as CaO2=1.34 × SpO2 × haemoglobin), but was reduced in patients with low FEV1 or VC. Supranormal work rates were seen in patients with severe right-to-left shunting and SpO2 < 90%, but only if FEV1 was >80% predicted. VSAQ-calculated METS also demonstrated little relationship with SpO2, and in crude and CaO2-adjusted regression, were lower in patients with lower FEV1 or VC. Bronchodilation increased airflow even where spirometry was in the normal range: exhaled nitric oxide measurements were normal in 80% of cases, and unrelated to any PAVM-specific variable. CONCLUSIONS: Exercise capacity is reduced by relatively mild airflow limitation (obstructive or restrictive) in the setting of PAVMs.


Subject(s)
Arteriovenous Malformations/physiopathology , Exercise Test , Exercise Tolerance , Hypoxia/etiology , Lung/physiopathology , Adolescent , Adult , Aged , Aged, 80 and over , Female , Forced Expiratory Volume , Humans , Linear Models , Male , Middle Aged , Prospective Studies , Pulmonary Artery/abnormalities , Pulmonary Veins/abnormalities , Spirometry , Vital Capacity , Young Adult
2.
Thorax ; 69(11): 1046-7, 2014 Nov.
Article in English | MEDLINE | ID: mdl-24713588

ABSTRACT

Postural changes in 258 patients with pulmonary arteriovenous malformations (PAVMs) reviewed between 2005 and 2013 were evaluated prospectively using validated pulse oximetry methods. Of the 257 completing the test, 75 (29%) demonstrated orthodeoxia with an oxygen saturation fall of at least 2% on standing. None described platypnoea (dyspnoea on standing). The heart rate was consistently higher in the erect posture: 74 (29%) had a postural orthostatic tachycardia of ≥20 min(-1), and in 25 (10%) this exceeded 30 min(-1). Orthostatic tachycardia was more pronounced in PAVM patients than controls without orthodeoxia (age-adjusted coefficient 5.5 (95% CIs 2.6, 8.4) min(-1), p<0.001). For PAVM patients, the age-adjusted pulse rise was 0.79 min(-1) greater for every 1% greater drop in oxygen saturation on standing (p<0.001). In contrast to the postural orthostatic tachycardia syndrome, in this population, there was a trend for more pronounced orthostatic tachycardia to be associated with better exercise tolerance.


Subject(s)
Arteriovenous Fistula/complications , Heart Rate/physiology , Posture , Pulmonary Artery/abnormalities , Pulmonary Veins/abnormalities , Tachycardia/etiology , Adolescent , Adult , Aged , Aged, 80 and over , Arteriovenous Fistula/diagnosis , Arteriovenous Fistula/physiopathology , Female , Follow-Up Studies , Humans , Male , Middle Aged , Oximetry , Prospective Studies , Pulmonary Artery/physiopathology , Pulmonary Veins/physiopathology , Tachycardia/diagnosis , Tachycardia/physiopathology , Time Factors , Young Adult
3.
Arch Dis Child ; 94(9): 674-80, 2009 Sep.
Article in English | MEDLINE | ID: mdl-19457879

ABSTRACT

OBJECTIVES: To describe and quantify the maternal and neonatal factors associated with Group B streptococcus (GBS) disease in infants <90 days of age. SETTING: Neonatal Units in London, Oxford, Portsmouth and Bristol. PATIENTS: Cases were infants <90 days of age with invasive GBS disease diagnosed between 2000 and 2003, and controls were healthy infants born in the same hospital and in the same birth weight category. MAIN OUTCOME MEASURES: Demographic and clinical data on the mother, baby, birth and neonatal stay. RESULTS: 138 cases and 305 controls were recruited. The majority of cases (74%) presented in the first week of life (early onset, EO); most on day 1 (89%). 65% of EO cases had one or more clinical risk factors (prematurity, prolonged rupture of membranes (PROM), known maternal GBS carriage, fever during labour). A multivariable logistic regression analysis found that the strongest independent associations with GBS disease were known maternal carriage of GBS (odds ratio (OR) 6.9), maternal infection in the peripartum period (OR 4.2) and maximum temperature in labour (OR 2.2 per degrees C). GBS disease was associated with twice the likelihood of PROM and fetal tachycardia (p = 0.05 and 0.07 respectively). EO cases had lower Apgar scores and were more likely to have respiratory distress and convulsions, and to require tube feeding than controls. They spent longer in hospital than controls, requiring longer stays at all levels of care. CONCLUSIONS: Independent of birth weight, a number of maternal, birth and neonatal factors are significantly associated with GBS disease. The management of babies with GBS disease results in an appreciable use of hospital resources.


Subject(s)
Infectious Disease Transmission, Vertical/statistics & numerical data , Pregnancy Complications, Infectious/epidemiology , Streptococcal Infections/epidemiology , Streptococcus agalactiae , Adolescent , Adult , Age of Onset , Analgesia, Epidural , Antibiotic Prophylaxis , Birth Weight , Case-Control Studies , Chi-Square Distribution , Female , Fetal Membranes, Premature Rupture , Fever , Heart Rate, Fetal , Humans , Incidence , Infant , Infant, Newborn , Infectious Disease Transmission, Vertical/prevention & control , Logistic Models , Pregnancy , Pregnancy Complications, Infectious/diagnosis , Risk Factors , Streptococcal Infections/diagnosis , Streptococcal Infections/transmission , United Kingdom/epidemiology , Young Adult
4.
Eur Respir J ; 32(1): 162-9, 2008 Jul.
Article in English | MEDLINE | ID: mdl-18385173

ABSTRACT

Increasing evidence supports the use of embolisation to treat pulmonary arteriovenous malformations (AVMs). Most pulmonary AVM patients have hereditary haemorrhagic telangiectasia (HHT), a condition that may be associated with pulmonary hypertension. The current authors tested whether pulmonary AVM embolisation increases pulmonary artery pressure (P(pa)) in patients without baseline severe pulmonary hypertension. P(pa) was measured at the time of pulmonary AVM embolisation in 143 individuals, 131 (92%) of whom had underlying HHT. Angiography/embolisation was not performed in four individuals with severe pulmonary hypertension, whose systemic arterial oxygen saturation exceeded levels usually associated with dyspnoea in pulmonary AVM patients. In 143 patients undergoing pulmonary AVM embolisation, P(pa) was significantly correlated with age, with the most significant increase occurring in the upper quartile (aged >58 yrs). In 43 patients with repeated measurements, there was no significant increase in P(pa) as a result of embolisation. In half, embolisation led to a fall in P(pa). The maximum rise in mean P(pa) was 8 mmHg: balloon test occlusion was performed in one of these individuals, and did not predict the subsequent rise in P(pa) following definitive embolisation of the pulmonary AVMs. In the present series of patients, which excluded those with severe pulmonary hypertension, pulmonary artery pressure was not increased significantly by pulmonary arteriovenous malformation embolisation.


Subject(s)
Arteriovenous Malformations/therapy , Embolization, Therapeutic/adverse effects , Hypertension, Pulmonary/etiology , Pulmonary Artery/abnormalities , Pulmonary Veins/abnormalities , Telangiectasia, Hereditary Hemorrhagic/complications , Adolescent , Adult , Aged , Aged, 80 and over , Child , Cohort Studies , Humans , Middle Aged
5.
Eur J Immunol ; 30(7): 1939-47, 2000 Jul.
Article in English | MEDLINE | ID: mdl-10940883

ABSTRACT

Immunostimulatory DNA sequences (ISS) are a potent Th1 adjuvant. We hypothesized that conjugation of ISS to protein antigens would strongly enhance their immunogenicity because both antigen and adjuvant (ISS) would be delivered to the same locale/antigen-presenting cell. To test this hypothesis, we conjugated a 22-mer immunostimulatory oligodeoxynucleotide (ISS-ODN) to two test antigens of differing intrinsic immunogenicity, namely Escherichia coli beta-galactosidase and the HIV-1 envelope glycoprotein gp120. We show that the antigen-ISS conjugates rapidly induce Th1 cells secreting high levels of IFN-gamma, strong CTL activity, and high titer IgG2a and HIV-neutralizing antibodies, exceeding gene and protein vaccination alone or immunization with mixtures of antigen and ISS-ODN. The data suggest that this procedure generates a novel and unique vaccine that rapidly triggers strong humoral and cell-mediated immunity.


Subject(s)
Antibodies, Bacterial/blood , HIV Antibodies/blood , HIV Envelope Protein gp120/immunology , Interferon-gamma/metabolism , Oligodeoxyribonucleotides/immunology , T-Lymphocytes, Cytotoxic/immunology , Th1 Cells/immunology , Thionucleotides/immunology , beta-Galactosidase/immunology , Animals , Antibodies, Bacterial/immunology , Antibody Formation/immunology , CHO Cells , Cricetinae , Electrophoresis, Polyacrylamide Gel/methods , Escherichia coli/enzymology , Female , HIV Antibodies/immunology , HIV Envelope Protein gp120/genetics , Immunity, Cellular/immunology , Immunoglobulin G/blood , Immunoglobulin G/immunology , Mice , Mice, Inbred BALB C , Plasmids/immunology , Sodium Dodecyl Sulfate , Th1 Cells/metabolism , Time Factors , beta-Galactosidase/genetics
6.
J Allergy Clin Immunol ; 106(1 Pt 1): 124-34, 2000 Jul.
Article in English | MEDLINE | ID: mdl-10887315

ABSTRACT

BACKGROUND: Allergen immunotherapy is inconvenient and associated with the risk of anaphylaxis. Efforts to improve the safety of immunotherapy by means of chemical modification of allergens have not been successful because it greatly reduced their antigenicity. Recently, immunostimulatory DNA sequences (ISS or CpG motifs) have been shown to act as strong T(H)1 response-inducing adjuvants. OBJECTIVE: We sought to determine whether conjugation of ISS to the major short ragweed allergen Amb a 1 results in enhanced immunotherapeutic potential in mice and decreased allergenicity in human subjects. METHODS: A 22-mer ISS oligodeoxynucleotide (ISS-ODN) was coupled to Amb a 1 and used for immunization of mice, rabbits, and monkeys. RESULTS: In mice the Amb a 1-ISS conjugate induced a T(H)1 response (IFN-gamma secretion), whereas Amb a 1 induced a T(H)2 response (IL-5 secretion). The T(H)1 response was not observed with an Amb a 1-non-ISS conjugate. Coinjection of Amb a 1 with ISS-ODN was much less effective in inducing a T(H)1 response. In mice primed for a T(H)2 response, injection with Amb a 1-ISS conjugate induced a de novo T(H)1 response and suppressed IgE antibody formation after challenge with Amb a 1. Amb a 1-ISS conjugate induced high-titer anti-Amb a 1 IgG antibodies in rabbits and cynomolgus monkeys, whereas Amb a 1 alone or Amb a 1 coinjected with ISS-ODN did not induce a detectable response. Amb a 1-ISS conjugate was less allergenic than Amb a 1 alone, as shown by a 30-fold lower histamine release from human basophils of patients with ragweed allergy, whereas mixing ISS-ODN with Amb a 1 did not reduce histamine release. CONCLUSION: Amb a 1-ISS conjugate has an enhanced T(H)1-biased immunogenicity and reduced allergenicity. It may offer a more effective and safer approach for allergen immunotherapy than currently available methods.


Subject(s)
Allergens/immunology , Pollen/immunology , Vaccines, DNA/immunology , Allergens/chemistry , Animals , Basophils/immunology , Enzyme-Linked Immunosorbent Assay , Female , Histamine Release , Humans , Immunoglobulin E/biosynthesis , Immunoglobulin G/biosynthesis , Interleukin-5/metabolism , Macaca fascicularis , Mice , Mice, Inbred BALB C , Pollen/chemistry , Rabbits , Spleen/metabolism , Structure-Activity Relationship , Th2 Cells/immunology , Vaccines, DNA/chemistry
7.
Methods Mol Med ; 29: 451-72, 2000.
Article in English | MEDLINE | ID: mdl-21374341

ABSTRACT

Allergic disorders are characterized by the prevalence of immunoglobulin (Ig) isotype E antibodies, and are considered to result from enhanced T helper type-2 (Th2) responses to allergens. A Th2 response is characterized by enhanced humoral responses and the production of IL-4 and IL-5 by CD4(+) T cells (Th2) in response to antigen (1,2). These "Th2 cytokines" enhance the allergic response by inducing B cell isotype switching to IgE (3-5), by inducing undifferentiated Th0 cells to further differentiate into Th2 cells, and by inducing eosinophil growth, and differentiation (5). In addition, the Th2 cytokines inhibit Th0 differentiation into Th1 cells, thereby reducing the recruitment of interferon gamma (IFN-γ) producing Th1 cells that could then down-regulate or modulate the Th2 responses (3,5). Consequently, the ability of a Th2 response to allergens to exert a positive feedback effect leads to a vicious cycle and may explain the exacerbation of allergic responses that follows continued exposure to allergens in atopic humans (2,6).

8.
J Immunol ; 163(9): 4721-7, 1999 Nov 01.
Article in English | MEDLINE | ID: mdl-10528170

ABSTRACT

DNA vaccines can stimulate both humoral and cytolytic immune responses. Although bone marrow-derived elements present the expressed Ag, the mechanisms for acquiring immunogenic peptides have yet to be fully elucidated. APCs may become directly transfected by plasmid DNA or process extracellular proteins produced by other transfected cells. Using a transactivating plasmid system and bone marrow chimeras, we show that both mechanisms appear to be involved; however, the bulk of the immune response is dependent on expression of Ag by nonlymphoid tissues and transfer to APCs. These in vivo studies are the first to define the role of transfected nonlymphoid cells in generating Ag for presentation by bone marrow-derived APCs after needle injection with plasmid DNA.


Subject(s)
Ovalbumin/genetics , Ovalbumin/immunology , Vaccines, DNA/immunology , Animals , Antibodies, Antinuclear/biosynthesis , Antigens, Surface/administration & dosage , Antigens, Surface/immunology , Antigens, Surface/metabolism , Bone Marrow/immunology , Bone Marrow/metabolism , Cell Membrane/immunology , Cell Membrane/metabolism , Cytotoxicity, Immunologic/genetics , Cytotoxicity, Immunologic/immunology , Injections, Intradermal , Macrophages/immunology , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Mice, Transgenic , Ovalbumin/administration & dosage , Plasmids/administration & dosage , Plasmids/immunology , Promoter Regions, Genetic/immunology , Skin/immunology , Spleen/cytology , Spleen/immunology , T-Lymphocytes, Cytotoxic/immunology , T-Lymphocytes, Cytotoxic/metabolism , Tetracycline/pharmacology , Trans-Activators/biosynthesis , Trans-Activators/immunology , Transfection , Vaccines, DNA/administration & dosage
9.
J Immunol ; 163(6): 3116-22, 1999 Sep 15.
Article in English | MEDLINE | ID: mdl-10477577

ABSTRACT

High-affinity pathologic rheumatoid factor (RF) B cells occur in autoimmune diseases such as rheumatoid arthritis, but are deleted in healthy individuals. The reasons for the survival and differentiation of these autoreactive B cells in rheumatoid arthritis are not known. Previous studies in mice transgenic for a human IgM RF have shown that peripheral encounter with soluble human IgG leads to deletion of high-affinity RF B cells; however, deletion can be prevented when concomitant T cell help is provided. This study aimed to further discern the minimal factors necessary not only for the in vivo survival of RF B cells, but also for their differentiation into Ab-secreting cells. The combination of MHC class II-reactive T cells and Ag induced the production of RF in human IgM RF transgenic mice, while either stimulus alone was ineffective. Neutralizing Abs against CD40 ligand (CD40L), but not against IL-4 or IL-15, abrogated IgM-RF production. Moreover, blockade of CD40L-CD40 allowed IgG to delete the RF precursor cells. Most importantly, activating Abs to CD40 could substitute entirely for T cell help in promoting the survival of RF precursors and in stimulating RF synthesis in T cell deficient animals. The data indicate that CD40 signaling alone can prevent deletion of RF B cells by Ag and in the presence of IgG is sufficient to trigger RF synthesis. The results suggest that selective induction of apoptosis in high-affinity RF B cells may be achieved by blockade of CD40L-CD40 interaction.


Subject(s)
Autoantigens/physiology , CD40 Antigens/physiology , Rheumatoid Factor/biosynthesis , Signal Transduction/immunology , Animals , Antibodies, Blocking/administration & dosage , Autoantigens/administration & dosage , B-Lymphocytes/immunology , B-Lymphocytes/pathology , CD40 Antigens/immunology , CD40 Ligand , Cell Survival/immunology , Cells, Cultured , Histocompatibility Antigens Class I/immunology , Humans , Immune Sera/pharmacology , Immunoglobulin G/pharmacology , Interleukin-15/administration & dosage , Interleukin-15/pharmacology , Interleukin-4/administration & dosage , Interleukin-4/pharmacology , Ligands , Lymphocyte Transfusion , Membrane Glycoproteins/antagonists & inhibitors , Membrane Glycoproteins/immunology , Mice , Mice, Inbred C57BL , Mice, Transgenic , Spleen/cytology , Spleen/transplantation , T-Lymphocytes, Helper-Inducer/immunology
10.
Pediatr Pulmonol Suppl ; 18: 118-21, 1999.
Article in English | MEDLINE | ID: mdl-10093118

ABSTRACT

The nature of the immune response (Th1/Th2) in mice to protein antigens or allergens was compared to that of immunization with pDNA encoding the same antigens. pDNA immunization induced a Th1 response and no IgE antibodies whereas the proteins induced a Th2 response and IgE antibodies. Furthermore, the pDNA induced Th1 response dominated over the protein elicited Th2 response in a secondary immune response. In particular, a preexisting Th2 response (as is the case in allergic patients) did not prevent a new Th1 response to an allergen-pDNA booster injection. The major reason why pDNA immunization induced a Th1 response to allergens was the presence of immunostimulatory non-coding DNA sequences (ISS) in the plasmid constructs having a CpG motif. These ISS caused antigen presenting cells to secrete INF-alpha, INF-beta and IL-12, all cytokines that induce naive T cells to differentiate into CD4+ Th1 cells and CD8+ Tc1 cells. Passive transfer of both Th1 and Tc1 cells from pDNA immunized mice into naive mice inhibited a Th2 response and IgE antibody formation to a subsequent injection of allergen in alum. pDNA immunization or ISS-oligonucleotide injection prior to allergen challenge reduced both immediate type airway sensitivity and late phase allergen induced eosinophil filtration of the lung. Allergen-pDNA immunization may provide a novel type of immunotherapy for the treatment of allergic diseases in man. Since only small amounts of allergen are secreted by the allergen-pDNA transformed cells, allergen-pDNA immunotherapy will unlikely carry the risk of the anaphylactic reactions that are associated with classical allergen injection immunotherapy.


Subject(s)
Antigens/genetics , Asthma/immunology , DNA/blood , DNA/immunology , Allergens/immunology , Animals , Asthma/therapy , Humans , Immunization , Immunotherapy/methods , Lung/immunology , Mice , Mice, Inbred BALB C , Th1 Cells/immunology , Th2 Cells/immunology
11.
Cell Immunol ; 191(1): 69-73, 1999 Jan 10.
Article in English | MEDLINE | ID: mdl-9918688

ABSTRACT

Normal individuals do not express the high-affinity autoantibodies specific for self-IgG (rheumatoid factors, RF) that are commonly seen in rheumatoid arthritis patients. Studies of transgenic mice expressing a human IgM rheumatoid factor have shown that one mechanism by which higher affinity RF B cells are tolerized to IgG is through abortive RF B cell activation followed by deletion in the absence of T cell help. We show that RF B cell deletion occurs through an intrinsic apoptotic mechanism that is independent of the Fas/FasL pathway and does not involve active killing by T cells, as it occurs in RAG-1-deficient RF transgenic mice to the same extent as in the parental RF transgenic line.


Subject(s)
Apoptosis , B-Lymphocytes/physiology , Immune Tolerance , Membrane Glycoproteins/physiology , Rheumatoid Factor/physiology , fas Receptor/physiology , Animals , Antigen-Presenting Cells/physiology , Fas Ligand Protein , Humans , Immunoglobulin G/physiology , Mice
12.
J Immunol ; 161(12): 7054-62, 1998 Dec 15.
Article in English | MEDLINE | ID: mdl-9862743

ABSTRACT

We have used a mouse model of allergen-induced airway hyperresponsiveness to demonstrate that immunostimulatory DNA sequences (ISS) containing a CpG DNA motif significantly inhibit airway eosinophilia and reduce responsiveness to inhaled methacholine. ISS not only inhibited eosinophilia of the airway (by 93%) and lung parenchyma (91%), but also significantly inhibited blood eosinophilia (86%), suggesting that ISS was exerting a significant effect on the bone marrow production of eosinophils. The inhibition of the bone marrow production of eosinophils by 58% was associated with a significant inhibition of T cell-derived cytokine generation (IL-5, granulocyte-macrophage CSF, and IL-3). ISS exerted this inhibitory effect on T cell cytokine production indirectly by stimulating monocytes/macrophages and NK cells to generate IL-12 and IFNs. The onset of the ISS effect on reducing the number of tissue eosinophils was both immediate (within 1 day of administration) and sustained (lasted 6 days), and was not due to ISS directly inducing eosinophil apoptosis. ISS was effective in inhibiting eosinophilic airway inflammation when administered either systemically (i.p.), or mucosally (i.e., intranasally or intratracheally). Interestingly, a single dose of ISS inhibited airway eosinophilia as effectively as daily injections of corticosteroids for 7 days. Moreover, while both ISS and corticosteroids inhibited IL-5 generation, only ISS was able to induce allergen-specific IFN-gamma production and redirect the immune system toward a Th1 response. Thus, systemic or mucosal administration of ISS before allergen exposure could provide a novel form of active immunotherapy in allergic diseases.


Subject(s)
Adjuvants, Immunologic/therapeutic use , Allergens/toxicity , Bronchial Hyperreactivity/prevention & control , CpG Islands , Interleukin-5/biosynthesis , Oligodeoxyribonucleotides/therapeutic use , Pulmonary Eosinophilia/prevention & control , Adjuvants, Immunologic/pharmacology , Administration, Intranasal , Animals , Anti-Inflammatory Agents/pharmacology , Anti-Inflammatory Agents/therapeutic use , Bone Marrow/pathology , Bronchial Hyperreactivity/etiology , Bronchial Hyperreactivity/immunology , Bronchial Provocation Tests , Desensitization, Immunologic , Dexamethasone/pharmacology , Dexamethasone/therapeutic use , Disease Models, Animal , Drug Evaluation, Preclinical , Eosinophils/pathology , Female , Granulocyte-Macrophage Colony-Stimulating Factor/biosynthesis , Hypereosinophilic Syndrome/etiology , Hypereosinophilic Syndrome/immunology , Hypereosinophilic Syndrome/prevention & control , Interferon-gamma/biosynthesis , Interleukin-3/biosynthesis , Methacholine Chloride , Mice , Mice, Inbred BALB C , Oligodeoxyribonucleotides/administration & dosage , Oligodeoxyribonucleotides/pharmacology , Ovalbumin/immunology , Plethysmography, Whole Body , Pulmonary Eosinophilia/etiology , Pulmonary Eosinophilia/immunology , Th2 Cells/immunology , Trachea/pathology
13.
J Immunol ; 161(10): 5720-32, 1998 Nov 15.
Article in English | MEDLINE | ID: mdl-9820554

ABSTRACT

In vitro studies of several naturally occurring proteins have characterized VH family-specific B lymphocyte binding and stimulatory properties that appear analogous to those of T cell superantigens. To examine the in vivo consequences of exposure to a putative B cell superantigen, we treated neonatal BALB/c mice with a form of staphylococcal protein A (MS) devoid of Fcgamma binding activity, which retains the clan VHIII Fab binding specificity. In naive adults, about 5% of peripheral B cells and >13% of splenic IgM-secreting cells display MS binding activity, in association with high IgM and low IgG circulating anti-MS Ab titers. Neonatal exposure to MS elicited two distinct temporal phases of immune responsiveness. The early phase, representing the first approximately 5 wk of life, was associated with MS-specific B cell and T cell tolerance. Microfluorometric assays revealed that exposure caused a dramatic MS-specific B cell clonal loss in bone marrow and spleen, but levels normalized by about 3 wk of life. The late phase (>6 wk of age) was associated with spontaneous priming for MS-specific T cell responses and production of MS-specific IgG1 Abs despite long term persistently depressed in vivo and in vitro MS-specific IgM responses. In vivo challenge during the late phase induced high frequencies of MS-specific IgG-secreting cells, indicating recruitment of highly focused Ab responses that were predominantly encoded by rearrangements of the S107 family, a member of the VHIII clan. These studies document the immunodominance of the VH-restricted Fab binding site on staphylococcal protein A and demonstrate the diverse effects of a B cell superantigen on the emerging peripheral B cell compartment.


Subject(s)
Animals, Newborn/immunology , Antibodies, Bacterial/biosynthesis , B-Lymphocytes/immunology , Immunoglobulin Heavy Chains/genetics , Immunoglobulin Variable Region/genetics , Staphylococcal Protein A/immunology , Superantigens/immunology , Animals , B-Lymphocytes/metabolism , B-Lymphocytes/microbiology , Gene Rearrangement, B-Lymphocyte, Heavy Chain , Genes, Immunoglobulin , Immunoglobulin Fab Fragments/metabolism , Immunoglobulin G/biosynthesis , Immunoglobulin M/biosynthesis , Injections, Intraperitoneal , Injections, Subcutaneous , Lymphocyte Count , Mice , Mice, Inbred BALB C , Multigene Family/immunology , Staphylococcal Protein A/administration & dosage , Staphylococcal Protein A/metabolism , Superantigens/administration & dosage
16.
J Immunol ; 159(10): 4999-5004, 1997 Nov 15.
Article in English | MEDLINE | ID: mdl-9366427

ABSTRACT

The interaction of the TCR with MHC class I-bound Ag is insufficient for the priming of CTL unless secondary costimulatory signals are provided. To ascertain the minimum elements required to activate an Ag-specific CTL response in vivo, we injected mice intradermally or i.m. with plasmid DNA encoding a MHC class I-restricted peptide Ag (minigene) and different membrane-bound costimulatory ligands. The minigene-encoded epitope only primed a specific CTL response if injected in the vicinity of an ectopically expressed costimulatory ligand. Vector encoding B7-1 was repeatedly more potent at stimulating a cytolytic response than vector encoding B7-2. In contrast the B7-2-encoding plasmid preferentially enhanced Ag-specific Ab responses when injected with either protein or a cDNA expression vector. Gene vaccination with plasmids encoding OVA and B7-1, but not B7-2, prolonged survival in mice challenged with an OVA-transfected tumor. These results show that functional B7-1 transfection can be achieved in vivo and induces the selective induction of CTL. The data suggest that B7-1 plasmids should be coadministered with naked DNA vaccines that aim to induce tumor-specific cellular immunity.


Subject(s)
DNA/immunology , Lymphocyte Activation , Tumor Escape/genetics , Animals , Antigens, CD/biosynthesis , Antigens, CD/physiology , B7-2 Antigen , Epitopes, T-Lymphocyte/genetics , Epitopes, T-Lymphocyte/immunology , Female , Histocompatibility Antigens Class I/genetics , Immunoglobulin G/biosynthesis , Ligands , Lymphocyte Activation/genetics , Membrane Glycoproteins/biosynthesis , Membrane Glycoproteins/physiology , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Neoplasm Transplantation , Ovalbumin/immunology , Plasmids/immunology , Sarcoma, Experimental , T-Lymphocytes, Cytotoxic/immunology , Thymoma , Tumor Cells, Cultured , Tumor Escape/immunology
17.
Int Arch Allergy Immunol ; 113(1-3): 227-30, 1997.
Article in English | MEDLINE | ID: mdl-9130530

ABSTRACT

BACKGROUND: We previously showed that immunization of mice with plasmid DNA (pDNA) encoding the Escherichia coli beta-galactosidase gene (pCMV-LacZ) induces a Th1 response, whereas beta-galactosidase (beta-gal) in saline or alum induces a Th2 response. Furthermore, the Th1 response dominates over the Th2 response and downregulates preexisiting IgE antibody formation. Here, we determined by passive transfer of CD4+ or CD8+ lymphocytes and by immunizing beta2-microglobulin knockout (beta2-M KO) mice whether CD4+ and/or CD8+ cells from pDNA-immunized mice suppress IgE antibody production. METHODS: BALB/c mice were injected with either CD4+ or CD8+ lymphocytes from naive beta-gal-in-alum or pCMV-LacZ-immunized mice, then immunized with beta-gal in alum, and the IgE antibody formation was determined. Second, C57BL/6 wild-type (WT) or beta2-M KO mice were immunized with beta-gal orpCMV-LacZ, and the IgE antibody production was assessed. RESULTS: Passive transfer of both CD4+ and CD8+ lymphocytes from pDNA-immunized mice suppressed the IgE antibody response by 90% compared to transfer of CD4+ T cells from naive or beta-galin-alum immunized mice. beta2-M KO mice produced 3 times more IgE than the WT control mice both in the primary and secondary response. CONCLUSION: Both CD4+ and CD8+ subsets of T cells from pDNA-immunized mice can suppress IgE antibody production by affecting the primary response and/or by propagating the Th1 memory response in a passive cell transfer system. Immunization with pDNA-encoding allergens may be an effective new form of immunotherapy for atopic diseases.


Subject(s)
CD4-Positive T-Lymphocytes/physiology , CD8-Positive T-Lymphocytes/physiology , Immunoglobulin E/biosynthesis , Vaccines, DNA/immunology , beta-Galactosidase/genetics , Animals , Immunization , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Mice, Knockout
18.
Proc Natl Acad Sci U S A ; 94(2): 646-51, 1997 Jan 21.
Article in English | MEDLINE | ID: mdl-9012838

ABSTRACT

Rheumatoid factor (RF) B cells proliferate during secondary immune responses to immune complexed antigen and antigen specific T cells, but higher affinity RFs are not detected except in patients with rheumatoid arthritis and other autoimmune diseases. Consequently, there must exist highly efficient mechanisms for inactivation of these higher-affinity RF B cell clones under normal circumstances. Exposure of transgenic mice expressing a human IgM RF to soluble human IgG in the absence of T cell help causes antigen specific B cell deletion in 2-3 days. The deletion is independent of the Fas/Fas ligand (FasL) pathway of apoptosis and is preceded by a phase of partial activation involving increase in cell size and expression of B7 and ICAM-1, and transient release of low levels of immunoglobulin. Complete B cell activation involving the formation of germinal centers and sustained high level RF secretion only occurs if T cell help is provided simultaneously. RF B cells exposed to tolerogen remain competent to secrete RF in vitro if provided with an appropriate antigenic stimulus and T cell help. Consequently, death of these cells is not preceded by anergy. Abortive activation/deletion of B cells by antigen in the absence of T cell-derived survival signals may represent the major mechanism for maintaining peripheral tolerance in B cells expressing higher affinity RF. The lack of anergy, and the potential for reactivation before death, provide a means for maintaining RF production under pathologic circumstances, such as may occur in the inflamed rheumatoid synovium.


Subject(s)
B-Lymphocytes/immunology , Immunoglobulin G/immunology , Rheumatoid Factor/immunology , Animals , Apoptosis , Humans , Immune Tolerance , Immunoglobulin G/chemistry , Immunoglobulin M/metabolism , Lymphocyte Activation , Lymphocyte Depletion , Mice , Mice, Transgenic , Receptors, Antigen, B-Cell/metabolism , Solubility
20.
J Exp Med ; 184(4): 1555-60, 1996 Oct 01.
Article in English | MEDLINE | ID: mdl-8879229

ABSTRACT

The injection of naked plasmid DNA directly into the muscle cells of mice has been shown to induce potent humoral and cellular immune responses. The generation of a cytotoxic T lymphocyte (CTL) response after plasmid DNA injection may involve the presentation of the expressed antigen in the context of the injected myocytes' endogenous major histocompatibility (MHC)-encoded class I molecules or may use the MHC molecules of bone marrow-derived antigen presenting cells (APC) which are capable of providing co-stimulation as well. To resolve which cell type provides the specific restricting element for this method of vaccination we generated parent-->F1 bone marrow chimeras in which H-2bxd recipient mice received bone marrow that expressed only H-2b or H-2d MHC molecules. These mice were injected intramuscularly with naked plasmid DNA that encoded the nucleoprotein from the A/PR/8/34 influenza strain, which as a single antigen has epitopes for both H-2Db and H-2Kd. The resulting CTL responses were restricted to the MHC haplotype of the bone marrow alone and not to the second haplotype expressed by the recipient's myocytes. The role of somatic tissues that express protein from injected plasmids may be to serve as a reservoir for that antigen which is then transferred to the APC. Consequently, our data show that the mechanism of priming in this novel method for vaccination uses the MHC from bone marrow-derived APC, which are efficient at providing all of the necessary signals for priming the T cell.


Subject(s)
Nucleoproteins/immunology , RNA-Binding Proteins , T-Lymphocytes, Cytotoxic/immunology , Vaccination/methods , Vaccines, DNA/immunology , Viral Core Proteins/immunology , Viral Vaccines/immunology , Animals , Antigen-Presenting Cells/immunology , Bone Marrow/immunology , Female , Histocompatibility Antigens/immunology , Injections, Intramuscular , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Nucleocapsid Proteins , Nucleoproteins/genetics , Plasmids/immunology , Radiation Chimera , Viral Core Proteins/genetics
SELECTION OF CITATIONS
SEARCH DETAIL
...