Search results for "Superantigens"
showing 10 items of 17 documents
Specific IgE against Staphylococcus aureus enterotoxins: an independent risk factor for asthma.
2012
The role of IgE in patients with severe asthma is not fully understood.We sought to investigate whether IgE to Staphylococcus aureus enterotoxins might be relevant to disease severity in adult asthmatic patients.Specific IgE antibody concentrations in serum against enterotoxins, grass pollen (GP), and house dust mite allergens and total IgE levels were measured in adult cohorts of 69 control subjects, 152 patients with nonsevere asthma, and 166 patients with severe asthma. Severe asthma was defined as inadequately controlled disease despite high-dose inhaled corticosteroids plus at least 2 other controller therapies, including oral steroids.Enterotoxin IgE positivity was significantly great…
Activation by mitogens and superantigens of axolotl lymphocytes: functional characterization and ontogenic study.
1996
Urodele amphibians have weak and slow immune responses compared to mammals and anuran amphibians. Using new culture conditions, we tested the ability of lymphocytes of a well-studied salamander, the Mexican axolotl (Ambystoma mexicanum) to proliferate in vitro with diverse mitogenic agents. We demonstrated that the axolotl has a population of B lymphocytes that proliferate specifically and with a high stimulation index to the lipopolysaccharide (LPS) known as a B-cell mitogen in mammals. This proliferative capacity is observed without significant changes throughout ontogenesis. In the presence of LPS, axolotl B lymphocytes are able to synthesize and secrete both isotopes of immunoglobulin d…
Staphylococcal food poisoning case and molecular analysis of toxin genes in Staphylococcus aureus strains isolated from food in Sicily, Italy.
2014
A case of staphylococcal food poisoning was observed in two individuals of the same family after consumption of primosale, a semiripened sheep cheese produced in Sicily. Staphylococcus aureus isolated from the cheese produced enterotoxin C (SEC) and carried both the enterotoxin C (sec) and the toxic shock syndrome toxin (tsst-1) gene. Following this case, an extensive survey was conducted on 971 food samples (raw milk, cheese, meat, and food preparations). S. aureus was detected in 102 of 971 food samples, from all types of food with the exception of ricotta cheese. The tsst-1 gene was present in 42% of the strains, either alone or in combination with other toxin genes. The enterotoxin C ge…
Prevention and reversal of superantigen-induced anergy by contact allergen exposure
1995
The superantigen Staphylococcal enterotoxin B (SEB) and the contact allergen 2,4-dinitrofluorbenzene (DNFB) both react with V beta 8+ T-cells delivering distinct signals. Pre-treatment with DNFB painted onto the same skin site where SEB was to be injected, prevented the induction of anergy in V beta + T-cells that was otherwise induced after SEB had been injected intradermally over a period of 2 weeks. Application of the irritant sodium dodecyl sulfate (SDS) instead of DNFB did not exert this effect. Application of DNFB at a site distant from the site where SEB was injected resulted in a much weaker inhibitory influence on the induction of anergy by SEB. Established anergy of V beta 8+ T-ce…
Distribution and kinetics of superantigen-induced cytokine gene expression in mouse spleen.
1993
The polyclonal stimulation of T cells by bacterial superantigens is involved in the pathogenesis of the toxic shock syndrome in certain staphylococcal and streptococcal infections. Here we describe the onset and kinetics of superantigen-induced cytokine production in situ in spleens of normal BALB/c mice monitored at the level of cytokine mRNA expression by in situ hybridization. Messenger RNAs for interleukin 2 (IL-2), interferon gamma, and tumor necrosis factors (TNF) alpha and beta were not expressed at detectable levels in spleens of unstimulated animals but became visible already 30 min after intraperitoneal application of 50 micrograms staphylococcal enterotoxin B. All mRNA levels sho…
Modulation of Contact Sensitivity Responses by Bacterial Superantigen
1995
Superantigens are potent modulators of the immune system, especially T cells. Therefore, we determined the influence of superantigens on the T-cell-mediated immune response, contact sensitivity. We chose the combination of staphylococcal enterotoxin B (SEB) as superantigen and 2,4-dinitrofluorbenzene (DNFB) as the contact sensitizer, because in BALB/c mice SEB reacts almost exclusively with V beta 8+ T cells, and these cells are capable of transferring contact sensitivity to DNFB from sensitized donors to naive syngeneic recipients. Pretreatment with a single intradermal injection of 50 ng SEB 24 h before DNFB exposure at the same site on the lower abdomen enhanced the induction of contact …
Distribution of emm types among group A streptococcal isolates from Serbia.
2010
AbstractThis is the first study concerning the molecular epidemiology of group A streptococcus in Serbia and includes 145 isolates from patients with various infections during the period 2001–2007. The emm types, superantigen profile and susceptibility pattern were determined. Among 31 emm types identified, the most prevalent were emm6, emm12, emm1, and emm58. All isolates showed uniform antimicrobial susceptibility to all tested antibiotics, with the exception of tetracycline and erythromycin (41% and 0.7% resistant strains, respectively). Significant heterogeneity of emm types was found, with a high frequency of emm6 and emm58, as well as a considerable prevalence of tetracycline resistan…
Major histocompatibility complex class II binding site for streptococcal pyrogenic (erythrogenic) toxin A.
1994
Streptococcal pyrogenic exotoxin A (SPEA) is an important pathogenicity factor of group A streptococci. It is a member of the family of „superantigens” produced by Staphylococcus aureus and Streptococcus pyogenes and its T lymphocyte stimulating activity is involved into the pathogenesis of certain diseases caused by pyogenic streptococci. In this study we have produced and characterized recombinant SPEA molecules in Escherichia coli. These molecules are indistinguishable from natural SPEA in both T cell stimulatory and HLA class II binding activities. Human class II molecules are more efficient than mouse class II molecules in presenting SPEA to T cells. In binding tests to major histocomp…
Natural and induced apoptosis during lymphocyte development in the axolotl
1999
Lymphocytes apoptosis was characterized in a urodele amphibian, the axolotl, by morphology using electron microscopy and by flow cytometry after propidium iodide staining, as well as by biochemical criteria with the detection of DNA ladders after glucocorticoid treatment. The morphological and biochemical features observed in treated axolotls are in accordance with the criteria of apoptosis found in different models of mammalian lymphocyte programmed cell death. The onset of natural apoptosis was then detected by DNA fragmentation in thymus and in spleen during lymphocyte development and ontogenesis. A typical DNA ladder characteristic of apoptosis is detectable in the thymus as early as 5 …
Report of toxic shock syndrome toxin 1 (TSST-1) from Staphylococcus aureus isolated in food handlers and surfaces from foodservice establishments.
2012
A set of 53 Staphylococcus aureus isolates collected from food handlers and foodservice establishments in Spain was analyzed for toxic shock syndrome toxin (TSST-1) production. S. aureus strains were isolated from 908 samples collected from different surfaces such as dish towels, workers’ hands, cutting boards, stainless steel tables and slicers, but they were not detected neither in clean plates nor in kitchen knives. Only one food worker hand has been reported to be contaminated by TSST-1 in a restaurant. Despite this, proper hygiene practices should be respected for the surfaces of contact with food, as well as for the hands of the manipulators This is the first article, in Spain, that r…