Sampling from Extracorporeal Circuit: A Step Forward for Dose Monitoring in Continuous Renal Replacement Therapy.

INTRODUCTION: Continuous renal replacement therapies (CRRTs) require constant monitoring and periodic treatment readjustments, being applied to highly complex patients, with rapidly changing clinical needs. To promote precision medicine in the field of renal replacement therapy and encourage dynamic prescription, the Acute Dialysis Quality Initiative (ADQI) recommends periodically measuring the solutes extracorporeal clearance with the aim of assessing the current treatment delivery and the gap from the therapeutic prescription (often intended as effluent dose). To perform this procedure, it is therefore necessary to obtain blood and effluent samples from the extracorporeal circuit to measure the concentrations of a target solute (usually represented by urea) in prefilter, postfilter, and effluent lines. However, samples must be collected simultaneously from the extracorporeal circuit ports, with the same suction flow at an unknown rate. METHODS: The proposed study takes the first step toward identifying the technical factors that should be considered in determining the optimal suction rate to collect samples from the extracorporeal circuit to measure the extracorporeal clearance for a specific solute. RESULTS: The results obtained identify the low suction rate (i.e., 1 mL/min) as an ideal parameter for an adequate sampling method. Low velocities do not perturb the external circulation system and ensure stability prevailing pressures in the circuit. Higher velocities can be performed only with blood flows above 120 mL/min preferably in conditions of appropriate filtration fraction. DISCUSSION/CONCLUSIONS: The specific value of aspiration flow rate must be proportioned to the prescription of CRRT treatments set by the clinician.

High proportion of inflammatory CD62Llow eosinophils in blood and nasal polyps of severe asthma patients.

BACKGROUND: In mice models, eosinophils have been divided into different subpopulations with distinct phenotypes and functions, based on CD62L and CD101 patterns of membrane expression. Limited data are available in humans. OBJECTIVE: To investigate eosinophils subpopulations in peripheral blood (PB) and nasal polyp tissue (NP) from severe eosinophilic asthma (SEA) patients plus concomitant chronic rhinosinusitis with nasal polyps (CRSwNP). METHODS: We recruited 23 SEA patients (14 with CRSwNP); as controls, we enrolled 15 non-severe asthma patients, 15 allergic rhinitis patients without asthma and 15 healthy donors. Eosinophils were isolated from PB and NP and analysed by FACS. Eotaxin-3 and eotaxin-1 mRNA expression in NP tissue was also evaluated. RESULTS: A significantly higher percentage of circulating CD62Llow cells was observed in SEA, as compared with controls, expressing higher levels of CCR3, CD69 and lower levels of CD125 (IL-5R), CRTH2, CD86 and CD28 in comparison with CD62Lbright cells. In NP, eosinophils showed a high proportion of CD62Llow phenotype, significantly greater than that observed in PB. Surface expression of IL-3R, IL-5R, CD69 and CD86 was significantly higher in CD62Llow eosinophils from NP than in those from blood. Moreover, eotaxin-3 mRNA expression positively correlated with the percentage of CD62Llow cells in NP. CONCLUSION: Two different eosinophil subphenotypes can be identified in blood and NP of SEA patients, with a preferential accumulation of CD62Llow inflammatory cells in NP.

Asthma and Chronic Rhinosinusitis: How Similar Are They in Pathogenesis and Treatment Responses?

Severe asthma and rhinosinusitis represent frequent comorbidities, complicating the overall management of the disease. Both asthma and chronic rhinosinusitis (CRS) can be differentiated into endotypes: those with type 2 eosinophilic inflammation and those with a non-type 2 inflammation. A correct definition of phenotype/endotype for these diseases is crucial, taking into account the availability of novel biological therapies. Even though patients suffering from type 2 severe asthma-with or without CRS with nasal polyps-significantly benefit from treatment with biologics, the existence of different levels of patient response has been clearly demonstrated. In fact, in clinical practice, it is a common experience that patients reach a good clinical response for asthma symptoms, but not for CRS. At first glance, a reason for this could be that although asthma and CRS can coexist in the same patient, they can manifest with different degrees of severity; therefore, efficacy may not be equally achieved. Many questions regarding responders and nonresponders, predictors of response, and residual disease after blocking type 2 pathways are still unanswered. In this review, we discuss whether treatment with biological agents is equally effective in controlling both asthma and sinonasal symptoms in patients in which asthma and chronic rhinosinusitis with nasal polyps coexist.

IL-10-Producing Infliximab-Specific T Cells Regulate the Antidrug T Cell Response in Exposed Patients.

Infliximab (IFX) is a chimeric mAb that can lead to the appearance of anti-drug Abs. Recent research has identified the presence of circulating IFX-specific T cells in treated patients. The aim of the study was to analyze the functional characteristics of IFX-specific T cells, in particular their capability to produce biologically active regulatory cytokines. Drug-stimulated PBMCs or coculture systems were used to detect memory T cells in treated patients. The cytokines produced by IFX-specific T cells, T cell lines, and T cell clones were evaluated at the mRNA and protein levels. Drug infusion induced an increase in IL-10 serum levels in vivo, whereas other cytokines were unchanged. IL-10 mRNA was higher in IFX-stimulated PBMCs from treated patients compared with untreated patients. When analyzed longitudinally, an early IL-10 mRNA expression was observed. HLA class II-restricted IL-10 production by drug-specific T cells from exposed patients was observed in different experimental settings, such as a coculture system, sorted CD154+ T cells, IFX peptide-stimulated PBMCs, and IFX-specific T cell clones. Finally, IL-10-producing drug-specific T cell clones downregulated the response of autologous effector T cells to IFX. Overall, these findings identify IFX-specific T cells as a source of biologically active IL-10 and suggest interference by IL-10-producing cells in the detection of drug-specific T cells.

Rapid clinical improvement of atopic dermatitis in an Omalizumab treated patient.

BACKGROUND: Atopic dermatitis is a chronic inflammatory skin disorder, whose symptoms and severity grossly depend on individual trigger factors. The majority of patients are satisfactorily treated with emollients together with topical and systemic therapies. However, treatment failure or long-term side effects with conventional treatment options can be a significant clinical problem. Recently, novel therapeutic approaches focus on targeting skewed immune responses providing a more effective, and less harmful approach. Among them, variable success has been reported using Omalizumab, when used in combination with classic therapies. This report describes an interesting case of severe adult onset difficult-to-treat atopic dermatitis dramatically improved in response to treatment with Omalizumab. CASE PRESENTATION: We present a case of an adult male with severe allergic atopic dermatitis, with concomitant involvement of the face, neckline, trunk and forearms and systemic symptoms such as diarrhoea with important decrease of his daily quality of life. The patient had been prescribed oral steroids in addition to anti-histamines to no avail. Due to lack of response to classic therapies, strict diet, as well as to treatment with intravenous corticosteroids, an off-label treatment with Omalizumab based on patient weight and total IgE value was proposed. Clear clinical results were observed after only a few weeks with regards to systemic symptoms, and just after 2 months of treatment in regards to skin involvement. CONCLUSIONS: In the majority of treated patients the clinical improvement of cutaneous manifestations is expected after several months of treatment, as skin manifestations are the consequence of a chronic inflammatory process. The outstanding rapid response observed in this case as well as the persistence of the clinical remission suggests that the block of the IgE pathways modulate functions of cells involved in the pathogenic mechanisms of chronic skin inflammation but also in the acute phases observed in the flare-ups of the disease.

Treatment with 8-OH-modified adenine (TLR7 ligand)-allergen conjugates decreases T helper type 2-oriented murine airway inflammation.

A strategy to improve allergen-specific immunotherapy is to employ new adjuvants stably linked to allergens. The study is addressed to evaluate the in vivo and in vitro effects of allergens [natural Dermatophagoides pteronyssinus 2 (nDer p 2) and ovalbumin (OVA)] chemically bound to an 8-OH-modified adenine. Humoral and cellular responses were analysed in allergen-sensitized and challenged mice by using conjugates (Conj) in a therapeutic setting. The in vitro activity of the conjugates on cytokine production induced by bone marrow dendritic cells and the co-culture system was also investigated. The nDer p 2-Conj treatment in nDer p 2-primed and challenged BALB/c mice reduced the numbers of eosinophils in bronchoalveolar lavage fluid and lung, airway allergen-driven interleukin-13 (IL-13) production in lung mononuclear cells and IgE, in comparison with nDer p 2-treated mice. The increase of IgG2a paralleled that of interferon-γ (IFN-γ) and IL-10 in allergen-stimulated spleen cells. Similar effects were elicited by treatment with OVA-Conj in an OVA-driven BALB/c model. The nDer p 2-Conj or OVA-Conj redirected memory T helper type 2 cells towards the production of IL-10 and IFN-γ also in C57BL/6 mice and when subcutaneously administered. Interleukin-10, IL-12 and IL-27 were produced in vitro by Conj-stimulated bone marrow dendritic cells, whereas IL-10 and IFN-γ were up-regulated in co-cultures of CD11c(+) and CD4(+) T cells from Conj-treated mice stimulated with allergen. Cytofluorometric analysis indicated that the Conj expanded IFN-γ- and IL-10- producing memory T cells. The Conj effects on IL-10(-/-) and IL-12(-/-) mice confirmed the role of IL-10 and IFN-γ in inducing a protective and balanced redirection the T helper type 2-mediated airway inflammation.

A novel allergen-adjuvant conjugate suitable for specific immunotherapy of respiratory allergy.

BACKGROUND: Several approaches to find a better adjuvant, focus immunomodulation, and reduce allergenicity are under investigation to improve the efficacy and safety of specific immunotherapy. OBJECTIVE: We performed an investigation of the in vitro and in vivo effects of a purified allergen chemically conjugated to a novel 8-OH modified adenine as an adjuvant. METHODS: Purified group 2 major allergen from house dust mite chemically conjugated to 4-(6-amino-9-benzyl-8-hydroxy-9H-purin-2-ylsulfanyl)-butyric acid succinimidyl ester was analyzed by using mass spectrometry. The adduct (nDer p 2-Conj) was assayed for Toll-like receptor activation on transfected HEK293 cells, stimulation of innate cells, and effects on the functional phenotype of specific T-cell lines and clones by means of flow cytometry, real-time PCR, and expression of TH-related transcription factors. Lung cells and sera of nDer p 2-Conj-sensitized C57Bl/6 mice were studied by means of cytology, histology, real-time PCR, and ELISA. RESULTS: nDer p 2-Conj stimulated IL-12 and IFN-α production from monocytes and plasmacytoid dendritic cells, respectively, retaining the ability to trigger Toll-like receptor 7 exclusively, and expanded human allergen-specific lymphocytes with reduced ability to produce T(H)2-related cytokines and increased IFN-γ levels, as based on GATA-3/T-bet expression. In vivo adduct-sensitized mice exhibited reduced eosinophil infiltration and IL-13 expression in the airways, IFN-γ upregulation together with IgE downregulation, and an increase in allergen-specific IgG(2a) levels in sera. The conjugate exhibited reduced ability to activate human FcεRI(+) cells without inducing T(H)17 cells or autoantibodies. CONCLUSIONS: The codelivery of an allergen with a modified adenine as a conjugate inducing modulatory cytokines from innate cells redirects in vitro and in vivo pathogenic TH2 responses without eliciting harmful effects.

Assays and strategies for immunogenicity assessment of biological agents.

Some patients with chronic inflammatory diseases either do not respond to or lose their initial responsiveness to Tumor Necrosis Factor (TNF) inhibitor therapy. In these patients, the clinical response after switching to another anti-TNF drug suggests that lack of response is not related to the therapeutic target itself but immunogenicity. All biologics are potentially immunogenic and can induce the development of antidrug antibodies (ADAs). ADA formation is associated with lower serum drug levels, infusion reactions, and loss of response. Analytical methods for ADA detection include enzyme-linked immunosorbent assay (ELISA), radioimmunoassay (RIA), surface plasmon resonance, and electrochemiluminescence. Currently, RIA and ELISA are the preferred methods due to a combination of reproducibility, sensitivity, and cost but have some limitations. There is no single available assay that has all pros and no cons, and therefore the use of more methods for the assessment of samples is a high priority.

Comparison of ELISA with automated ECLIA for IL-6 determination in COVID-19 patients: An Italian real-life experience.

Objectives: Coronavirus disease 2019 (COVID-19) has a wide spectrum of clinical severity. A cytokine storm is associated with COVID-19 severity. Of these, IL-6 is significantly associated with higher mortality and is also a marker for predicting disease prognosis. IL-6 may act as a target for therapeutics and, a blockade of IL-6 function by Tocilizumab has been described as a treatment of the inflammatory process COVID-19-related. This study aims to describe our experience comparing two different methods, in detail Human IL-6 Instant ELISA and the Elecsys IL-6 based on ECLIA, for the IL-6 assessment. Design and methods: IL-6 levels from serum samples of 104 COVID-19 patients, admitted to the AOU Careggi (Hospital in Florence -Italy), were assessed by using the two above-mentioned methods, and the results were analysed through Passing-Bablok regression fit and Bland-Altman plot. Results: The regression exhibited a linear relation between the methods with a regression equation (y = - 0.13 + 0.63 x; 95 % C.I. intercept = - 0.13 to 4.55; 95 % C.I. slope = 1.03 to 1.26 with R2 = 0.89, p > 0.05), showing a positive slope. The agreement of the two methods reported a bias of -25.0 pg/mL. Thus, the two methods correlate but do not agree in terms of numeric results. Conclusions: The two assays showed good comparability. However, because of the extremely wide linear range of the ECLIA, its throughput and its capacity for immune profiling, it represents an interesting emerging technology in the immunology field.

The TLR7 ligand 9-benzyl-2-butoxy-8-hydroxy adenine inhibits IL-17 response by eliciting IL-10 and IL-10-inducing cytokines.

This study evaluates the ability of a novel TLR7 ligand (9-benzyl-2-butoxy-8-hydroxy adenine, called SA-2) to affect IL-17 response. The SA-2 activity on the expression of IL-17A and IL-17-related molecules was evaluated in acute and chronic models of asthma as well as in in vivo and in vitro α-galactosyl ceramide (α-GalCer)-driven systems. SA-2 prepriming reduced neutrophils in bronchoalveolar lavage fluid and decreased methacoline-induced airway hyperresponsiveness in murine asthma models. These results were associated with the reduction of IL-17A (and type 2 cytokines) as well as of molecules favoring Th17 (and Th2) development in lung tissue. The IL-17A production in response to α-GalCer by spleen mononuclear cells was inhibited in vitro by the presence of SA-2. Reduced IL-17A (as well as IFN-γ and IL-13) serum levels in mice treated with α-GalCer plus SA-2 were also observed. The in vitro results indicated that IL-10 produced by B cells and IL-10-promoting molecules such as IFN-α and IL-27 by dendritic cells are the major player for SA-2-driven IL-17A (and also IFN-γ and IL-13) inhibition. The in vivo experiments with anti-cytokine receptor Abs provided evidence of an early IL-17A inhibition essentially due to IL-10 produced by resident peritoneal cells and of a delayed IL-17A inhibition sustained by IFN-α and IL-27, which in turn drive effector T cells to IL-10 production. These findings suggest that such TLR7 agonist downregulating Th17 (as well as Th2) response has to be considered a valid candidate for novel vaccine formulations in allergy.

Drug-specific Th2 cells and IgE antibodies in a patient with anaphylaxis to rituximab.

Rituximab (RTX) is currently used in the treatment of lymphoproliferative diseases and of several rheumatologic disorders and is a frequent cause of acute infusion reactions, usually classified as cytokine release syndrome (CRS). Some infusion reactions to RTX raise concern for immediate type I hypersensitivity, even if to date RTX-specific IgE antibodies have not been reported. To improve knowledge of the mechanisms of reactions to RTX, we investigated humoral and cellular immune responses to this drug in a patient suffering from rheumatoid arthritis who displayed two immediate infusion-related reactions. RTX-exposed tolerant patients and healthy untreated subjects were used as controls. Non-isotype-specific and IgE anti-RTX antibodies were positive in the serum samples collected from the reactive patient but not in those from the control groups. Only the reactive patient also displayed skin testing positivity with RTX. More importantly, RTX-stimulated peripheral blood mononuclear cells from the reactive patient, but not from the controls, displayed a dose-dependent proliferative response associated with a Th2 cytokine production profile. Our results show the presence of RTX-specific Th2-type cells and IgE antibodies, thus suggesting that type I hypersensitivity may be an additional mechanism to CRS in the development of RTX reactions.

Modified adenine (9-benzyl-2-butoxy-8-hydroxyadenine) redirects Th2-mediated murine lung inflammation by triggering TLR7.

Substitute adenine (SA)-2, a synthetic heterocycle chemically related to adenine with substitutions in positions 9-, 2-, and 8- (i.e., 9-benzyl-2-butoxy-8-hydroxyadenine), induces in vitro immunodeviation of Th2 cells to a Th0/Th1 phenotype. In this article, we evaluate the in vivo ability of SA-2 to affect Th2-mediated lung inflammation and its safety. TLR triggering and NF-kappaB activation by SA-2 were analyzed on TLR-transfected HEK293 cells and on purified bone marrow dendritic cells. The in vivo effect of SA-2 on experimental airway inflammation was evaluated in both prepriming and prechallenge protocols by analyzing lung inflammation, including tissue eosinophilia and goblet cell hyperplasia, bronchoalveolar lavage fluid cell types, and the functional profile of Ag-specific T cells from draining lymph nodes and spleens. SA-2 induced mRNA expression and production of proinflammatory (IL-6, IL-12, and IL-27) and regulatory (IL-10) cytokines and chemokines (CXCL10) in dendritic cells but down-regulated TGF-beta. Prepriming administration of SA-2 inhibited OVA-specific Abs and Th2-driven lung inflammation, including tissue eosinophilia and goblet cells, with a prevalent Foxp3-independent regulatory mechanism. Prechallenge treatment with SA-2 reduced the lung inflammation through the induction of a prevalent Th1-related mechanism. In this model the activity of SA-2 was route-independent, but adjuvant- and Ag dose-dependent. SA-2-treated mice did not develop any increase of serum antinuclear autoantibodies. In conclusion, critical substitutions in the adenine backbone creates a novel synthetic TLR7 ligand that shows the ability to ameliorate Th2-mediated airway inflammation by a complex mechanism, involving Th1 redirection and cytokine-mediated regulation, which prevents autoreactivity.

Strategies Targeting Type 2 Inflammation: From Monoclonal Antibodies to JAK-Inhibitors.

Bronchial asthma and its frequent comorbidity chronic rhinosinusitis (CRS), are characterized by an inflammatory process at lower and upper respiratory tract, with a variability in terms of clinical presentations (phenotypes) and distinct underpin pathophysiological mechanisms (endotypes). Based on the characteristics of inflammation, bronchial asthma can be distinguished into type 2 (eosinophilic) or nontype 2 (noneosinophilic) endotypes. In type 2 asthma endotype, the pathogenic mechanism is sustained by an inflammatory process driven by Th2 cells, type 2 innate lymphoid cells (ILC2) and type 2 cytokines, which include interleukin (IL)-4, IL-5, IL-9 and IL-13. The definition of asthma and chronic rhinusinusitis phenotype/endotype is crucial, taking into account the availability of novel biologic agents, such as monoclonal antibodies targeting the classical type 2 cytokines. Recently, new therapeutic strategies have been proposed and analyzed in preliminary clinical trials. Among them Janus kinase (JAK) inhibitors, now largely used for the treatment of other chronic inflammatory diseases such as rheumatoid arthritis and inflammatory bowel diseases, is receiving great relevance. The rationale of this strategy derives from the data that JAK is a tyrosine kinase involved in the signaling of T cell receptor and of several cytokines that play a role in allergic respiratory disease, such as IL-2, IL-4 and IL-9. In this review, we discuss whether treatment with biological agents and JAK inhibitors may be equally effective in controlling type 2 inflammatory process in both asthma and CRS.

Immunogenicity-unwanted immune responses to biological drugs - can we predict them?

INTRODUCTION: Biological agents (BAs) target molecules involved in disease mechanisms and have modified the natural history of several immune-mediated disorders. All BAs are immunogenic, resulting in the formation of antidrug antibodies (ADAs), which can neutralize drug activity leading to loss of response and potential relapse, or serious adverse events such as infusion hypersensitivity reactions. The production of ADAs is the result of a specific adaptive immune response in which T and B cells are involved. AREAS COVERED: Factors conditioning the immunogenicity of BAs, including drug-, treatment- and patient-related factors are currently the subject of many studies. Among them, a lot of attention is dedicated to define the impact of BAs structure, the effect of targeting (soluble or membrane) molecules, the impact of interruption of therapy as well as the role of genetic (HLA and non-HLA) predisposing factors and disease activity. EXPERT OPINION: Knowledge of factors capable of influencing the immunogenicity of BAs may help to understand, in a predictive manner and at the single patient level, the presence of risk factors influencing the production of ADAs and their impact on clinical outcomes.

How to Prevent and Mitigate Hypersensitivity Reactions to Biologicals Induced by Anti-Drug Antibodies?

Biologicals are widely used therapeutic agents for rheumatologic diseases, cancers, and other chronic inflammatory diseases. They are characterized by complex structures and content of variable amounts of foreign regions, which may lead to anti-drug antibodies (ADA) development. ADA onset may limit the clinical usage of biologicals because they may decrease their safety. In fact they are mainly associated with immediate hypersensitivity reactions (HSRs). Development of ADAs is reduced by concomitant immunosuppressive treatment, while it is increased by longer intervals between drug administrations; thus, regular infusion regimens should be preferred to reduce HSRs. Once ADAs have formed, some procedures can be implemented to reduce the risk of HSRs. ADAs may belong to different isotype; the detection of IgE ADA is advisable to be assessed when high and early ADAs are detected, in order to reduce the risk of severe HRs. In patients who need to reintroduce the biological culprit, as alternative therapies are not available, drug desensitization (DD) may be applied. Desensitization should be conceptually dedicated to patients with an IgE-mediated HSR; however, it can be performed also in patients who had developed non-IgE-mediated HSRs. Although the underlying mechanisms behind successful DD has not been fully clarified, the DD procedure is associated with the inhibition of mast cell degranulation and cytokine production. Additionally, some data are emerging about the inhibition of drug-specific immune responses during DD.

Drug-specific Treg cells are induced during desensitization procedure for rituximab and tocilizumab in patients with anaphylaxis.

Biologic agents (BA) are able to induce an adaptive immune response in a proportion of exposed patients with the onset of anti-drug antibodies (ADA), which are usually responsible for hypersensitivity reactions (HR). Drug desensitization (DD) for BA allows transient clinical tolerance to the drug in reactive patients. The paper aimed to analyse the modification of drug-specific immune responses along DD in two patients with previous ADA-mediated HR (anaphylaxis) to rituximab and tocilizumab. The in vivo and in vitro assays of humoral and cellular response to drugs were carried out in a longitudinal manner throughout the DD cycles. We observed a progressive decrease of the pre-procedure ADA titer with negativization during the DD cycles in both patients. The monitoring of the drug-specific effector cell response showed the decrease in the BA-induced proliferation, while T cell response to unrelated antigens resulted unmodified along the DD cycles. Lastly, the increase of circulating drug-specific Treg cells mainly producing IL-35 were shown during the DD treatment. This study provides evidence that DD treatment to two BA inhibits humoral and cellular anti-drug response by increasing regulatory T cells and cytokines in an antigen-restricted manner. These modifications could contribute to the safety of the procedure.

The anti-IgE monoclonal antibody omalizumab as adjuvant treatment in desensitization to carboplatin in patients with ovarian cancer.

•Ovarian cancer is the most lethal among gynecological cancers.•Carboplatin-based chemotherapy identifies as the main systemic treatment for ovarian cancer patients.•Almost one every three patients treated with carboplatin experiences hypersensitivity reactions.•Patients may experience breakthrough reactions during drug desensitization.•Omalizumab represents a promising new treatment to overcome carboplatin hypersensitivity.

Anaphylactic reactions to biological drugs.

PURPOSE OF REVIEW: This review summarizes the current knowledge of the pathogenic mechanisms of biologics-induced anaphylaxis, and the diagnostic and prophylactic strategies in the management of potentially reactive patients, to improve the safety profile of biologics. RECENT FINDINGS: The recent knowledge on the topic highlights the involvement of both effector and regulatory mechanisms in the immune response to biological agents. In addition, the impact of biological's immunogenicity on hypersensitivity reactions has been confirmed in a wider number of studies, defining some details about the kinetics of antidrug antibodies development, specifically immunoglobulin G (IgG) and immunoglobulin E (IgE). SUMMARY: Biological agents may induce anaphylaxis, mainly through the induction of antidrug antibodies. Biologics-related infusion reactions are often clinically consistent with type I hypersensitivity, but IgG antidrug antibodies may also be involved. The immune response toward biologicals is orchestrated by both effector and regulatory T cells. In addition, nonantibody-dependent mechanisms may occur. Among clinicians persists today again a low awareness, not only of the possibility to understand the immunological mechanisms behind anaphylaxis to biologicals but also the opportunity to apply potential strategies for the management of reactive patients aimed to guarantee a safe retreatment.

Systemic hypereosinophilic syndromes: when autoimmunity is Th2 mediated.

PURPOSE OF REVIEW: Clinical conditions associated with hypereosinophilia represent a field of particular interest, taking into account the epidemiological impact of the different primary and secondary forms. In addition to a classical Th1 response, also Th2 cells can be involved in the pathogenesis of autoimmune diseases, among them eosinophilic forms such as eosinophilic granulomatosis with polyangiitis. RECENT FINDINGS: In patients with severe asthma, recent evidence highlights the role of pathogenic autoantibodies against autologous eosinophil proteins (e.g. eosinophil peroxidase) suggest the role of autoimmune mechanisms, particularly in patients in which asthma is included in eosinophilic vasculitis with antineutrophilic autoantibody positivity. Is now evident that in addition to Th2 cells, also type 2 innate lymphoid cells and Th1/Th17 cells play a central role in the pathogenesis of hypereosinophilic syndrome. SUMMARY: The definition of cellular and molecular mechanisms and the critical role of specific cytokines involved in the pathogenesis of hypereosinophilic syndrome open the way to new therapeutic strategies by using biological agents targeting these specific factors.