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Allergy is a Th2-mediated disease that involves the formation of specific IgE antibodies against innocuous environmental substances. The prevalence of allergic diseases has dramatically increased over the past decades, affecting up to 30% of the population in industrialized countries. The understanding of mechanisms underlying allergic diseases as well as those operating in non-allergic healthy responses and allergen-specific immunotherapy has experienced exciting advances over the past 15 years. Studies in healthy non-atopic individuals and several clinical trials of allergen-specific immunotherapy have demonstrated that the induction of a tolerant state in peripheral T cells represent a key step in healthy immune responses to allergens. Both naturally occurring thymus-derived CD4 1 CD25 1 FOXP3 1 Treg and inducible type 1 Treg inhibit the development of allergy via several mechanisms, including suppression of other effector Th1, Th2, Th17 cells; suppression of eosinophils, mast cells and basophils; Ab isotype change from IgE to IgG4; suppression of inflammatory DC; and suppression of inflammatory cell migration to tissues. The identification of the molecules involved in these processes will contribute to the development of more efficient and safer treatment modalities.Key words: Allergy . Allergen-specific immunotherapy . Tolerance . Treg IntroductionThe immune system is a complex interactive network with the capacity to protect the host from a broad range of pathogens while keeping a state of tolerance to self and innocuous non-self antigens. Immune tolerance-related diseases such as allergy, autoimmunity, tumor tolerance and rejection of organ transplants arise as a direct consequence of dysregulated immune responses. The main clinical manifestations of allergy encompass allergic rhinitis, allergic asthma, food allergy, atopic eczema/ dermatitis and anaphylaxis. Currently, allergen-specific immunotherapy (allergen-SIT) by administration of increasing doses of allergen extracts remains as the single curative treatment of allergic diseases with the potential to modify the course of the disease [1].Adoptive transfer experiments in mouse models of allergy and asthmatic inflammation have shown that Treg are essential for the induction and maintenance of immune tolerance to allergens [2]. In humans, studies on immune responses to allergens in healthy individuals have demonstrated the existence of dominant Treg subsets specific to common environmental allergens [3]. In addition, allergen-SIT represents the only clinically established treatment that induces antigen-specific Treg and peripheral tolerance with the capacity to restore homeostasis in human subjects [3][4][5][6][7][8]. Accordingly, active immune regulation through allergen-specific Treg emerges as a potential therapeutic option 1232Review in the prevention and cure of allergic diseases. The aim of this review is to discuss the immune regulation mechanisms operating in allergic diseases with a focus on the role of Treg in the generation of tolerance agai...

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Resistance rates to amikacin, ciprofloxacin, ceftazidime, cefepime, imipenem, cefoperazone/sulbactam and piperacillin/tazobactam in Escherichia coli (n= 438), Klebsiella pneumoniae (n= 444), Pseudomonas aeruginosa (n= 210) and Acinetobacter baumanni (n=200) were determined with e-test in a multicenter surveillance study (Hitit-2) in 2007. ESBL production in Escherichia coli and K. pneumoniae was investigated following the CLSI guidelines. Overall 42.0% of E.coli and 41.4% of K. pneumoniae were ESBL producers. In E. coli , resistance to imipenem was not observed, resistance to ciprofloxacin and amikacin was 58.0% and 5.5% respectively. In K. pneumoniae resistance to imipenem, ciprofloxacin and amikacin was 3.1%, 17.8% 12.4% respectively. In P. aeruginosa the lowest rate of resistance was observed with piperacillin/tazobactam (18.1%). A. baumanni isolates were highly resistant to all the antimicrobial agents, the lowest level of resistance was observed against cefoperazone/sulbactam (52.0%) followed by imipenem (55.5%). this study showed that resistance rates to antimicrobials are high in nosocomial isolates and show variations among the centers.