Contribution of histamine metabolism to tachyphylaxis during the buildup phase of rush immunotherapy

Successful Desensitization to the Radiocontrast Material Iohexol (Omnipaque™)

Adverse reactions to radiocontrast media (RCM) are rare and occur predominantly in association with intravenous administration but may also occur with intra-arterial and nonvascular injections (e.g., retrograde pyelography, intra-articular injections) of RCM. This article reports the case of a 52-year-old lady who was known to have amyloidosis secondary to rheumatoid arthritis and was on regular renal replacement therapy. She was under follow-up for regular angioplasties to manage the central vein stenosis that was affecting her right brachiocephalic arteriovenous fistula (AVF) and was referred to our Immunology service when she developed an allergic reaction after her AVF angioplasty (central venoplasty). Despite being dialysed immediately post-angioplasty, she complained of skin rash and itching with hoarseness of voice that developed almost six to eight hours post-angioplasty. We decided to arrange the iodinated non-ionic iso-osmolar contrast agent iodixanol (Visipaque™) for her instead, as it is known to be better tolerated in patients with reactions to Omnipaque™ due to its lower osmolarity as compared to Omnipaque™. However, since it was the first time to request this contrast in our hospital, it was not possible due to logistical reasons. It was necessary that our patient continued to undergo angioplasty every three months, however, she was developing more severe and earlier symptoms with each subsequent exposure to the radiocontrast medium. After her latest reaction of generalized itching and angioedema with shortness of breath during the procedure despite premedication, it was decided for her to undergo desensitization to Omnipaque™. In the absence of a published protocol for this, we used a protocol used for desensitization to Visipaque™. She showed an excellent response and completed her remaining angioplasties until Visipaque™ became available. Hence, desensitization to Omnipaque™ using the published protocol to Visipaque™ is likely to help patients allergic to Omnipaque™ or where Visipaque™ is not available or non-affordable in low/middle-income countries.

Time-dependent effect of desensitization with wasp venom on selected parameters of the immune system

The emergence of tolerance during Hymenoptera venom immunotherapy (VIT) is a complex process. The main goal of VIT is to induce a change from proinflammatory Th2 response to the Th1 response. However, the immune mechanism of acquiring rapid tolerance during VIT has not yet been fully understood. Therefore, we have analyzed (in 4-time points: 0, 2, 6, and 24 weeks after the initiation phase of VIT) the concentration of complement C3, C4, and C5 components, lymphocyte subpopulations (flow cytometry), as well as histamine and tryptase serum concentrations of 43 patients with wasp venom allergy (III and IV Müller grade) classified to ultra-rush treatment and 18 volunteers as the control group (CG). We observed that VIT affected the immune system by inducing changes in the complement system (decreased C3 and C4 compartment protein concentrations) and "normalized" the percentage of lymphocytes and neutrophils in the peripheral blood. Moreover, a significant increase in the percentage of nTreg in the blood of patients treated with VIT was observed. On the other hand, there were no changes in histamine or tryptase concentrations in the blood. Increased percentage of nTreg cells is a well-known mechanism by which VIT affects the immune system. Finally, VIT also modulated the concentrations of the complement components, which may be a previously unknown VIT mechanism of action.

Usefulness of Rapid Desensitization Therapy for Severe Rash Caused by Molecularly Targeted Drugs Used in the Treatment of Non-small-cell Lung Cancer

Molecular-targeted drugs (MTDs), such as epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) and anaplastic lymphoma kinase inhibitors, are used to treat non-small-cell lung cancer (NSCLC). The incidence of rash caused by EGFR-TKIs and discontinuation of MTDs because of rash are issues. Rapid desensitization therapy (RDT) was performed in five patients who developed severe rash after introduction of MTDs and was successful in four, all of whom showed no rash relapse. RDT may thus be useful for treating rash in patients receiving MTDs for NSCLC.

Hymenoptera Venom Allergy: How Does Venom Immunotherapy Prevent Anaphylaxis From Bee and Wasp Stings?

Hymenoptera stings may cause both local and systemic allergic reactions and even life threatening anaphylaxis. Along with pharmaceutical drugs and foods, hymenoptera venom is one of the most common causes of anaphylaxis in humans. To date, no parameter has been identified that may predict which sensitized people will have a future systemic sting reaction (SSR), however some risk factors, such as mastocytosis and age >40 years are known. Venom immunotherapy (VIT) is the most effective method of treatment for people who had SSR, which is shown to be effective even after discontinuation of the therapy. Development of peripheral tolerance is the main mechanism during immunotherapy. It is mediated by the production of blocking IgG/IgG4 antibodies that may inhibit IgE dependent reactions through both high affinity (FcεRI) and low affinity (FcεRII) IgE receptors on mast cells, basophils and B cells. The generation of antigen specific regulatory T cells produces IL-10 and suppresses Th2 immunity and the immune responses shift toward a Th1-type response. B regulatory cells are also involved in the production of IL-10 and the development of long term immune tolerance. During VIT the number of effector cells in target organs also decreases, such as mast cells, basophils, innate type 2 lymphocytes and eosinophils. Several meta-analyses and randomized controlled studies have proved that VIT is effective for preventing SSR to a sting and improves the quality of life. In this review, the risk of SSR in venom allergy and how VIT changed this risk are discussed.

Skin inflammation exacerbates food allergy symptoms in epicutaneously sensitized mice

BACKGROUND

Cutaneous exposure to food antigen through impaired skin barrier has been shown to induce epicutaneous sensitization, thereby causing IgE-mediated food allergies.

OBJECTIVE

We examined whether skin barrier impairment following epicutaneous sensitization exacerbates food allergies.

METHODS

BALB/c mice were epicutaneously sensitized by repeated application of ovalbumin (OVA) to MC903-pretreated ear skin for 48 hours weekly and then intragastrically challenged with OVA. After the first oral challenge, the skin barrier was disrupted with topical application of MC903 or by tape-stripping. Mice were monitored for changes in body temperature and the occurrence of diarrhea after undergoing the second oral challenge. Serum levels of mouse mast cell protease-1 (mmcp1) and OVA-specific IgE, IgG1, IgG2a antibodies and OVA-specific IgA levels in intestinal lavage fluid were measured by ELISA. Tissue accumulation of eosinophils was determined histologically.

RESULTS

Epicutaneously sensitized mice developed anaphylaxis after intragastric challenge, as evidenced by diarrhea, decreased body temperature, and increased serum mmcp1 levels. Skin barrier disruption by MC903 treatment or tape-stripping exacerbated allergic reactions induced by oral challenge. MC903 treatment increased serum baseline and postchallenge mmcp1 levels. Topical pretreatment with dexamethasone alleviated allergic reactions that were exacerbated by MC903 treatment.

CONCLUSION

Even after eliminating exposure to the antigen, inflammation from skin barrier disruption can exacerbate the severity of food allergy symptoms. Serum baseline mmcp1 levels might be an effective marker for predicting the severity of antigen-induced allergic symptoms.

The usefulness of the basophil activation test in monitoring specific immunotherapy with house dust mite allergens

Introduction

In clinical practice, reliable tools for monitoring specific immunotherapy (SIT) are of utmost importance.

Aim

To assess the usefulness of the basophil activation test (BAT) in monitoring SIT in paediatric patients with allergy to house dust mites (HDM).

Material and methods

Thirty-one children qualified for SIT with HDM, of whom 21 completed the SIT during the observation period. The BAT was carried out prior to commencing the SIT (time point BAT1) and upon finishing the initial pack of allergy vaccine (cumulative dose of allergen 12487.5 PNU; BAT2), as well as after the second vaccine pack (cumulative dose of allergen 23750.0 PNU; BAT3). Peripheral blood of the patients was stimulated with allergen solutions in five concentrations from 0.00225 ng/ml to 22.5 ng/ml. Basophil activation was measured by CD63 expression in flow cytometry.

Results

For the allergen concentration of 0.225 ng/ml, a statistically significant decrease in median basophil activation was observed, from 51.29% at BAT1 to 8.48% at BAT2 (p = 0.004) and 4.21% at BAT3 (p < 0.001). For the allergen concentration of 0.0225 ng/ml, a statistically significant decrease was seen between BAT1 (1.72%) and BAT3 (0.21%, p = 0.01). Median CD-sens index decreased significantly from 1099.02 at BAT1 to 179.31 at BAT2 (p < 0.002) and 168.04 at BAT3 (p < 0.001).

Conclusions

There is a significant decrease in BAT results in the course of specific immunotherapy with HDM allergens in children, with the optimum allergen concentration for monitoring basophil response at 0.225 ng/ml. The CD-sens index seems to be a better monitoring parameter than the plain percentage of CD63-expressing basophils.

Modified Allergens for Immunotherapy

PURPOSE OF REVIEW

During the past few decades, modified allergens have been developed for use in allergen-specific immunotherapy (AIT) with the aim to improve efficacy and reduce adverse effects. This review aims to provide an overview of the different types of modified allergens, their mechanism of action and their potential for improving AIT.

RECENT FINDINGS

In-depth research in the field of allergen modifications as well as the advance of recombinant DNA technology have paved the way for improved diagnosis and research on human allergic diseases. A wide range of structurally modified allergens has been generated including allergen peptides, chemically altered allergoids, adjuvant-coupled allergens, and nanoparticle-based allergy vaccines. These modified allergens show promise for the development of AIT regimens with improved safety and long-term efficacy. Certain modifications ensure reduced IgE reactivity and retained T cell reactivity, which facilities induction of immune tolerance to the allergen. To date, multiple clinical trials have been performed using modified allergens. Promising results were obtained for the modified cat, grass and birch pollen, and house dust mite allergens. The use of modified allergens holds promise for improving AIT efficacy and safety. There is however a need for larger clinical studies to reliably assess the added benefit for the patient of using modified allergens for AIT.

Modulation of immune responses by immunotherapy in allergic diseases

Allergen immunotherapy (AIT) has been used for 100 years and until now different immunoregulatory pathways have been shown to take place in its mechanisms of action. It is characterized by administration of the causative allergen and is shown to be clinically efficient even after discontinuation of therapy particularly in allergic respiratory diseases, bee venom allergy, and food allergy. Generation of antigen/allergen-specific peripheral tolerance is the key mechanism during immunotherapy. It is mediated by development of T and B regulatory cells, IgG4 isotype allergen-specific antibodies and the involvement of multiple suppressor factors, which lead to decreased tissue inflammation, early and late phase responses. Describing novel regulatory mechanisms in the process of immune tolerance induction will help to identify treatment modalities not only for allergic disorders, but also for autoimmune diseases, organ transplantation, chronic infections, and cancer.

Early suppression of basophil activation during allergen-specific immunotherapy by histamine receptor 2

BACKGROUND

Early desensitization of FcεRI-bearing mast cells and basophils has been demonstrated in allergen-specific immunotherapy and drug desensitization. However, its mechanisms have not been elucidated in detail. Histamine is one of the main mediators released on FcεRI triggering of basophils and mast cells, and it exerts its functions through histamine receptors (HRs).

OBJECTIVES

We sought to investigate HR expression on basophils of patients undergoing venom immunotherapy (VIT) and its effect on allergen, IgE, and FcεRI cross-linking-mediated basophil function and mediator release.

METHODS

Basophils were purified from the peripheral blood of patients undergoing VIT and control subjects and were studied functionally by using real-time PCR, flow cytometry and ELISA assays.

RESULTS

Rapid upregulation of H2R within the first 6 hours of the build-up phase of VIT was observed. H2R strongly suppressed FcεRI-induced activation and mediator release of basophils, including histamine and sulfidoleukotrienes, as well as cytokine production in vitro.

CONCLUSION

Immunosilencing of FcεRI-activated basophils by means of selective suppression mediated by H2R might be highly relevant for the very early induction of allergen tolerance and the so-called desensitization effect of VIT.

Early markers for protective mechanisms during rush venom immunotherapy

BACKGROUND

Allergen-specific venom immunotherapy (VIT) represents the only rational-based option to treat allergic sensitizations against bee and wasp venom. So far, there is not much knowledge about early induction of protective and tolerogenic pathways during VIT.

OBJECTIVES

To identify the earliest markers for protective mechanisms against allergic reactions in the peripheral blood during the build-up phase of VIT.

METHODS

PBMC and monocytes were isolated, and serum samples were taken before and during a five day build-up phase from 65 hymenoptera venom allergic patients. Expression level of tolerogenic markers was analyzed on mRNA and protein level. Serum levels of different soluble tolerogenic factors were measured.

RESULTS

We observed significantly enhanced tryptophan degradation, elevated ILT4 expression of monocytes as well as IL-10 production of CD3(+) T cells only a few hours after the first injection on day 1, followed by increased IL-10 serum levels, monocyte apoptosis and elevated intracellular cAMP levels of monocytes on day 3 combined with a higher ILT3 protein expression and IL-10 secretion of monocytes on day 5.

CONCLUSION

From these data, we conclude that tryptophan depletion, ILT3/4-mediated inhibition, higher IL-10 production as well as intracellular cAMP might contribute to early induction of protective mechanisms against allergic reactions during the build-up phase of VIT.

Advances in environmental and occupational respiratory diseases in 2009

The year 2009 led to a number of significant advances in environmental and occupational allergic diseases. The role of exposure to environmental pollutants, respiratory viruses, and allergen exposure showed significant advances. New allergens were identified. Occupational asthma and the relationship of complementary and alternative medicine to allergic diseases were extensively reviewed. New approaches to immunotherapy, novel vaccine techniques, and methods to reduce risks for severe allergic disease were addressed.

Advances in allergic skin disease, anaphylaxis, and hypersensitivity reactions to foods, drugs, and insects in 2009

This review highlights some of the research advances in anaphylaxis and hypersensitivity reactions to foods, drugs, and insects, as well as advances in allergic skin disease that were reported in the Journal in 2009. Among key epidemiologic observations, several westernized countries report that more than 1% of children have peanut allergy, and there is some evidence that environmental exposure to peanut is a risk factor. The role of regulatory T cells, complement, platelet-activating factor, and effector cells in the development and expression of food allergy were explored in several murine models and human studies. Delayed anaphylaxis to mammalian meats appears to be related to IgE binding to the carbohydrate moiety galactose-alpha-1,3-galactose, which also has implications for hypersensitivity to murine mAb therapeutics containing this oligosaccharide. Oral immunotherapy studies continue to show promise for the treatment of food allergy, but determining whether the treatment causes tolerance (cure) or temporary desensitization remains to be explored. Increased baseline serum tryptase levels might inform the risk of venom anaphylaxis and might indicate a risk for mast cell disorders in persons who have experienced such episodes. Reduced structural and immune barrier function contribute to local and systemic allergen sensitization in patients with atopic dermatitis, as well as increased propensity of skin infections in these patients. The use of increased doses of nonsedating antihistamines and potential usefulness of omalizumab for chronic urticaria was highlighted. These exciting advances reported in the Journal can improve patient care today and provide insights on how we can improve the diagnosis and treatment of these allergic diseases in the future.