Mechanisms of immunotherapy: IgG revisited

Recombinant allergen-based monitoring of antibody responses during injection grass pollen immunotherapy and after 5 years of discontinuation

BACKGROUND

Subcutaneous injection immunotherapy (SCIT) is considered as antigen-specific and disease-modifying treatment with long-lasting effect.

METHODS

We used a panel of recombinant grass pollen allergens for analyzing allergen-specific IgE, IgG(1) -IgG(4) , IgM, IgA, and light-chain (kappa, lambda) responses in grass pollen-allergic patients who had received one course of injection immunotherapy (SCIT) with an aluminum hydroxide-adsorbed grass pollen extract or only anti-inflammatory treatment. Serum samples were analyzed before and after 5 months of treatment as well as after 5 years.

RESULTS

After 5 months of SCIT but not of anti-inflammatory treatment, IgG(1) > IgG(4) > IgG(2) > IgA antibody responses using both kappa and lambda light chains specific for major grass pollen allergens (Phl p 1, Phl p 5, Phl p 6, Phl p 2) increased significantly, whereas specific IgM or IgG(3) levels were unaltered. Allergen-dependent basophil degranulation was only inhibited with SCIT sera containing therapy-induced allergen-specific IgG antibodies. Likewise, decreases in Phl p 1- and Phl p 5-specific IgE levels and significant (P<0.001) reduction in symptom and medication scores were found only in the SCIT group but not in the group of patients receiving anti-inflammatory treatment. After 5 years, allergen-specific IgG antibody levels in the SCIT group had returned to baseline levels and there was no significant difference regarding symptoms between the SCIT and non-SCIT groups.

CONCLUSION

The results from our observational study demonstrate that only SCIT but not anti-inflammatory treatment induces allergen-specific IgG and reduces boosts of allergen-specific IgE production but that one SCIT course was not sufficient to achieve long-term immunological and clinical effects.

Molecular diagnosis of egg allergy

PURPOSE OF REVIEW

Allergy to hen's egg is common in infancy and childhood. Oral food challenges are often required to diagnose egg allergy, because of the limitation in the diagnostic accuracy of skin test and specific IgE to egg white. New molecular diagnostic technologies have been recently introduced into allergological research. In this article, we will review the recent literature regarding the potential value of these tests for the clinical management of egg-allergic patients.

RECENT FINDINGS

Component-resolved diagnosis that can be combined with the microarray technology is promising as measurement of specific IgE antibodies to individual egg white components has been shown to predict different clinical patterns of egg allergy. Specific IgE to ovomucoid has been identified as a risk factor for persistent allergy and could indicate reactivity to heated egg. Ovomucoid and ovalbumin IgE and IgG4-binding epitope profiling could also help distinguish different clinical phenotypes of egg allergy. Particularly, egg-allergic patients with IgE antibodies reacting against sequential epitopes tend to have more persistent allergy.

SUMMARY

Using recombinant allergens, IgE-binding epitopes, and microarrays, molecular-based technologies show promising results. However, none of these tests is ready to be used in clinical practice and oral food challenge remains the standard for the diagnosis of egg allergy.

Hymenoptera venom immunotherapy

Subcutaneous venom immunotherapy is the only effective treatment for patients who experience severe hymenoptera sting-induced allergic reactions, and the treatment also improves health-related quality of life. This article examines advances in various areas of this treatment, which include the immunological mechanisms of early and long-term efficacy, indications and contraindications, selection of venom, treatment protocols, duration, risk factors for systemic reactions in untreated and treated patients as well as for relapse following cessation of treatment. Current and future strategies for improving safety and efficacy are also examined. However, although progress in the past few years has been fruitful, much remains to be accomplished.

Allergen-specific IgG antibody levels modify the relationship between allergen-specific IgE and wheezing in childhood

BACKGROUND

An increase in IgE antibody levels to inhalant allergens is associated with an increased likelihood of wheezing. The role of allergen-specific IgG and IgG4 in relation to wheezing is yet to be determined.

OBJECTIVE

We sought to investigate whether Fel d 1-specific IgG and IgG4 antibodies modify the association between cat allergen-specific IgE and childhood wheezing.

METHODS

We used data from 2 population-based birth cohorts (United Kingdom [UK], n = 473; Australia, n = 1336). Current wheeze was defined as wheezing in the previous 12 months at age 5 (UK) and 14 (Australia) years. We determined cat allergen-specific IgE (whole extract) and IgG and IgG4 antibody (purified rFel d 1) levels and used logistic regression to estimate the relationship between wheeze and the quantitative allergen antibody levels.

RESULTS

In the univariate analysis risk of wheezing increased significantly with increasing cat-specific IgE levels (UK: odds ratio [OR], 1.56; 95% CI, 1.28-1.90; Australia: OR, 1.29; 95% CI, 1.19-1.40). rFel d 1-specific IgG or IgG4 had no significant effect on wheeze in either population. However, a different pattern of the relationship between antibody levels and wheezing emerged in the multivariate analysis. In the UK cat-specific IgE increased the risk of wheeze (OR, 2.01; 95% CI, 1.29-3.12; P = .002), whereas rFel d 1-specific IgG decreased the risk (OR, 0.46; 95% CI, 0.21-0.99; P = .05). This finding was replicated in Australia (IgE: OR, 1.46; 95% CI, 1.28-1.68; P < .001; IgG: OR, 0.66; 95% CI, 0.44-0.99; P = .049). There was no significant association between IgG4 antibody levels and wheezing in either population.

CONCLUSIONS

rFel d 1-specific IgG but not IgG4 antibody levels significantly modify the association between cat-specific IgE and childhood wheezing, with the risk of symptoms decreasing with increasing IgG levels.

Facilitated antigen presentation and its inhibition by blocking IgG antibodies depends on IgE repertoire complexity

BACKGROUND

The antibody repertoires of allergic subjects are characterized by the presence of allergen-specific IgE antibodies. We have previously shown that the composition of the IgE repertoire is critical for allergen-mediated activation of human effector cells. Activation of CD4(+) T cells in allergic subjects is highly potentiated by the process of facilitated antigen presentation (FAP), in which allergen in complex with IgE is taken up by B cells through the low-affinity IgE receptor CD23 and presented to T cells.

OBJECTIVE

We sought to investigate the influence of IgE repertoire complexity on the formation of IgE/allergen/CD23 complexes on B cells and subsequent T-cell activation.

METHODS

Using defined allergen-specific recombinant IgE and IgG antibodies, we investigated the influence of individual IgE affinity, IgE clonality, specific IgE concentration, and the ratio between IgE specificities on IgE/allergen/CD23 complex formation in vitro.

RESULTS

Although IgE affinity is an important factor, IgE clonality seems to be governing complex formation, especially with medium- and low-affinity IgE antibodies. We demonstrate that differences in allergen-specific IgE affinity correlate with the efficiency of subsequent T-cell activation. In addition, we show that the complexity of an IgE repertoire also affects the ability of allergen-specific IgG antibodies to block FAP.

CONCLUSION

The composition of allergen-specific IgE repertoires in individual patients, especially with respect to IgE clonality, might play an important role in the manifestation of allergic disease not only for the immediate allergic reaction through activation of basophils and mast cells but also for the exacerbation of allergic inflammation through recurring activation of allergen-specific T cells by FAP.

Mechanisms of allergen-specific immunotherapy

Allergen-specific immunotherapy has been used for 100 years as a desensitizing therapy for allergic diseases and represents the potentially curative and specific method of treatment. The mechanisms of action of allergen-specific immunotherapy include the very early desensitization effects, modulation of T-and B-cell responses and related antibody isotypes, and migration of eosinophils, basophils, and mast cells to tissues, as well as release of their mediators. Regulatory T (Treg) cells have been identified as key regulators of immunologic processes in peripheral tolerance to allergens. Skewing of allergen-specific effector T cells to a regulatory phenotype appears as a key event in the development of healthy immune response to allergens and successful outcome in patients undergoing allergen-specific immunotherapy. Naturally occurring forkhead box protein 3-positive CD4(+)CD25(+) Treg cells and inducible T(R)1 cells contribute to the control of allergen-specific immune responses in several major ways, which can be summarized as suppression of dendritic cells that support the generation of effector T cells; suppression of effector T(H)1, T(H)2, and T(H)17 cells; suppression of allergen-specific IgE and induction of IgG4; suppression of mast cells, basophils, and eosinophils; and suppression of effector T-cell migration to tissues. New strategies for immune intervention will likely include targeting of the molecular mechanisms of allergen tolerance and reciprocal regulation of effector and Treg cell subsets.

Passive immunization with allergen-specific antibodies

The induction of allergen-specific IgG antibodies has been identified as a major mechanism responsible for the reduction of allergic inflammation in allergic patients treated by allergen-specific immunotherapy. Several studies suggest that allergen-specific IgG antibodies induced by vaccination with allergens block mast cell and basophil degranulation, IgE-facilitated allergen presentation to T cells and IgE production. The availability of recombinant allergens and technologies for the production of recombinant human antibodies allows engineering of allergen-specific antibodies which can be used for passive immunization (i.e., therapy) and eventually for the prevention of allergy (i.e., prophylaxis). This chapter summarizes data supporting the possible use of allergen-specific antibodies for treatment and prophylaxis. Finally, concrete approaches for the treatment and prevention of allergy based on blocking antibodies are envisioned.

The role of hen's egg-specific IgE, IgG and IgG4 in the diagnostic procedure of hen's egg allergy

BACKGROUND

Hen's egg (HE) allergy is a common disease in childhood. HE-specific serum IgE has been correlated with the outcome of oral food challenge tests, and diagnostic decision points have been described as helpful but still not sufficient to reduce the requirement for oral food challenges. The aim of the study was to correlate HE-specific IgE, IgG and IgG4 levels with the outcome of double-blind, placebo-controlled food challenges (DBPCFC) in patients with suspected HE allergy to improve diagnostic procedures.

METHODS

HE-specific IgE, IgG, and IgG4 levels were compared between 150 children with suspected HE allergy based on sensitization and/or patient's history who underwent DBPCFC. Sixty-six patients were HE-allergic (HE-sensitized with a positive DBPCFC), 48 HE-sensitized but tolerant (negative DBPCFC), and 36 patients were nonsensitized and tolerant (negative DBPCFC). Prior to food challenge HE-specific serum IgE, IgG, and IgG4 were measured with the Phadia CAP-system.

RESULTS

HE-specific IgE was significantly higher in HE-allergic patients than in clinically tolerant ones. However, there was no difference in HE-specific IgG and IgG4 concentrations between the patient groups.

CONCLUSION

A proposed cut-off level of 12 kU/l IgE would identify children above this level correctly as HE-allergic. The level of HE-specific IgG or IgG4 in serum of children with suspected HE allergy does not add any additional information in the diagnostic procedure of HE allergy. For diagnostic purposes, specific IgG or IgG4 should not routinely be tested.

Specific immunotherapy suppresses Th2 responses via modulating TIM1/TIM4 interaction on dendritic cells

BACKGROUND

Specific immunotherapy (SIT) is the only curable remedy for allergic disorders currently; however, the underlying mechanism is not fully understood yet. This study aimed to elucidate the mechanism of SIT on suppressing TIM4 (T cell immunoglobulin mucin domain molecule 4) expression in dendritic cells (DCs) and modulating the skewed T helper 2 (Th2) responses in patients with airway allergy.

METHODS

Twenty patients with allergic rhinitis (AR) were treated with SIT for 3 months. Before and after SIT, the expression of TIM4 in peripheral DC and TIM1 in Th2 cells was examined. The role of Fc gamma receptor (FcgammaR) I and II in modulating the expression of TIM4 in DCs was investigated.

RESULTS

The interaction of TIM1/TIM4 played a critical role in sustaining the polarization status of Th2 cells in AR patients. Cross-linking FcgammaRI by antigen/IgG complexes increased the production of TIM4 by dendritic cells via upregulating tumor necrosis factor-alpha in DCs. Exposure to microbial products promoted the expression of FcgammaRI in DCs that further increased the expression of TIM4. Exposure to specific antigens alone upregulated the expression of FcgammaRII in DCs, that suppressed the expression of TIM4.

CONCLUSIONS

We conclude that SIT suppresses the skewed Th2 responses via disrupting the interaction of TIM1/TIM4 in antigen-specific Th2 cells.

Mechanisms of allergen-specific desensitization

BACKGROUND

Allergen-specific desensitization (SIT) is the most effective therapy for allergies. Although allergen-specific antibodies have an important role in the process, mechanisms of IgG-mediated inhibition of allergic reactions are not well defined.

OBJECTIVE

We investigated mechanisms by which SIT-induced allergen-specific IgGs inhibit allergic reactions.

METHODS

We generated mAbs that recognize 3 nonoverlapping epitopes of the major cat allergen Fel d 1. Each of the mAbs was produced as an IgE and different IgG isotype.

RESULTS

IgEs against 2 nonoverlapping epitopes on Fel d 1 are necessary and sufficient to sensitize mast cells for maximal FcepsilonRI signaling and degranulation on exposure to monomeric Fel d 1. IgE antibodies of a third specificity did not further increase mast cell degranulation, indicating that formation of large FcepsilonRI clusters are not required to induce maximal activation of mast cells. A single IgG that was specific for an epitope different from those recognized by the IgEs was a potent inhibitor of Fel d 1-mediated mast cell activation in vitro and in vivo. This inhibition required Fcgamma receptor-IIB. In human beings, IgGs of a single specificity were able to block degranulation of basophils from individuals with cat allergy. The inhibitory potential of these antibodies increased when larger allergen-IgG complexes were formed.

CONCLUSIONS

These data reconcile conflicting theories in the literature and might explain the reason IgE levels do not necessarily decrease during therapy, despite clinical efficacy. These findings have important implications for vaccine design.

Allergen-specific subcutaneous immunotherapy in allergic asthma: immunologic mechanisms and improvement

Allergic asthma is a disease characterized by persistent allergen-driven airway inflammation, remodeling, and airway hyperresponsiveness. CD4(+) T-cells, especially T-helper type 2 cells, play a critical role in orchestrating the disease process through the release of the cytokines IL-4, IL-5, and IL-13. Allergen-specific immunotherapy (SIT) is currently the only treatment with a long-term effect via modifying the natural course of allergy by interfering with the underlying immunological mechanisms. However, although SIT is effective in allergic rhinitis and insect venom allergy, in allergic asthma it seldom results in complete alleviation of the symptoms. Improvement of SIT is needed to enhance its efficacy in asthmatic patients. Herein, the immunoregulatory mechanisms underlying the beneficial effects of SIT are discussed with the ultimate aim to improve its treatment efficacy.

Tracking antigen-specific T-cells during clinical tolerance induction in humans

Allergen immunotherapy presents an opportunity to define mechanisms of induction of clinical tolerance in humans. Significant progress has been made in our understanding of changes in T cell responses during immunotherapy, but existing work has largely been based on functional T cell assays. HLA-peptide-tetrameric complexes allow the tracking of antigen-specific T-cell populations based on the presence of specific T-cell receptors and when combined with functional assays allow a closer assessment of the potential roles of T-cell anergy and clonotype evolution. We sought to develop tools to facilitate tracking of antigen-specific T-cell populations during wasp-venom immunotherapy in people with wasp-venom allergy. We first defined dominant immunogenic regions within Ves v 5, a constituent of wasp venom that is known to represent a target antigen for T-cells. We next identified HLA-DRB1*1501 restricted epitopes and used HLA class II tetrameric complexes alongside cytokine responses to Ves v 5 to track T-cell responses during immunotherapy. In contrast to previous reports, we show that there was a significant initial induction of IL-4 producing antigen-specific T-cells within the first 3–5 weeks of immunotherapy which was followed by reduction of circulating effector antigen-specific T-cells despite escalation of wasp-venom dosage. However, there was sustained induction of IL-10-producing and FOXP3 positive antigen-specific T cells. We observed that these IL-10 producing cells could share a common precursor with IL-4-producing T cells specific for the same epitope. Clinical tolerance induction in humans is associated with dynamic changes in frequencies of antigen-specific T-cells, with a marked loss of IL-4-producing T-cells and the acquisition of IL-10-producing and FOXP3-positive antigen-specific CD4+ T-cells that can derive from a common shared precursor to pre-treatment effector T-cells. The development of new approaches to track antigen specific T-cell responses during immunotherapy can provide novel insights into mechanisms of tolerance induction in humans and identify new potential treatment targets.

From allergen genes to allergy vaccines

IgE-mediated allergy is a hypersensitivity disease affecting more than 25% of the population. The structures of the most common allergens have been revealed through molecular cloning technology in the past two decades. On the basis of this knowledge of the sequences and three-dimensional structures of culprit allergens, investigators can now analyze the immune recognition of allergens and the mechanisms of allergic inflammation in allergic patients. Allergy vaccines have been constructed that are able to selectively target the aberrant immune responses in allergic patients via different pathways of the immune system. Here we review various types of allergy vaccines that have been developed based on allergen structures, results from their clinical application in allergic patients, and future strategies for allergen-specific immunotherapy and allergy prophylaxis.

IgG antibodies produced during subcutaneous allergen immunotherapy mediate inhibition of basophil activation via a mechanism involving both FcgammaRIIA and FcgammaRIIB

The majority of human subjects who receive subcutaneous allergen immunotherapy (IT) develop decreased sensitivity to their allergens. Multiple factors may explain the efficacy of IT, some evidence support a role for allergen specific IgG antibodies. There is controversy whether such antibodies act by blocking allergen binding to IgE or initiation of active inhibitory signaling through low affinity IgG receptors (FcgammaRIIB) on mast cells and basophils. In this study, we addressed this question using peripheral blood from cat non-allergic, cat allergic, and immunotherapy-treated cat allergic subjects. Blood from subjects who received IT contain IgG antibodies that mediate inhibition of basophil activation by a mechanism that is blocked by antibodies specific for the inhibitory IgG receptor FcgammaRIIB. Surprisingly, inhibition was also blocked by aglycosylated, putatively non-FcR binding, antibodies that are specific for the FcgammaRIIA, suggesting a contribution of this receptor to the observed effect. Consistent with a cooperative effect, ex vivo basophils were found to express both IgG receptors. In other studies we found that basophils from subjects who were both chronically exposed to allergen and were producing both cat allergen specific IgE and IgG, are hyporesponsive to allergen. These studies confirm that IgG antibodies produced during IT act primarily by stimulation of inhibitory signaling, and suggest that FcgammaRIIA and FcgammaRIIB function cooperatively in activation of inhibitory signaling circuit. We suggest that under normal physiologic conditions in which only a small proportion of FcepsilonRI are occupied by IgE of a single allergen specificity, FcgammaRIIA co-aggregation may, by providing activated Lyn, be required to fuel activation of inhibitory FcgammaRIIB function.

Birch pollen immunotherapy leads to differential induction of regulatory T cells and delayed helper T cell immune deviation

Correction of an imbalance between allergen-specific T cell subsets is considered a critical event in establishing allergen tolerance by specific immunotherapy (SIT). In a comprehensive, longitudinal study, distinct T cell populations and Ig subtypes were analyzed in subjects allergic to birch pollen during decisive time points of SIT (i.e., induction and maintenance phase), as well as in and out of birch pollen season. An increase in Bet v 1-specific, IL-10-secreting T cells, fulfilling the criteria of inducible type 1 regulatory T (Tr1) cells, was observed by the end of the induction phase; this resulted in a decreased ratio of allergen-specific IL-5(+) Th2/Tr1 cells. In contrast, CD4(+)CD25(+)CD127(low) regulatory T cell numbers did not change. Furthermore, enhanced concentrations of allergen-specific IgG Abs were observed, whereas allergen-specific IgE and IgA levels remained unchanged. After 1 y of SIT, a reduced ratio of allergen-specific Th2/IFN-gamma(+) Th1 cells was apparent. Although untreated and SIT-treated allergic subjects developed enhanced Th2 cell responses during birch pollen season, only SIT-treated patients experienced elevated numbers of allergen-specific Tr1 cells, which were associated with reduced skin prick test reactivity and diminished clinical symptoms. In coculture assays, allergen-specific Tr1 cells showed an IL-10- and dose-dependent inhibition of CD4(+)CD25(-) T effector cells. Thus, SIT has differential effects on regulatory T cell subsets, resulting in an early induction of allergen-specific Tr1 cells associated with an increase in allergen-specific IgG, and it leads to a delayed shift from an allergen-specific Th2- to a Th1-dominated immune response.

Therapeutic manipulation of immune tolerance in allergic disease

Immune tolerance - the adaptation of the immune system to external antigens or allergens - might be therapeutically manipulated to restore normal immunity in conditions such as allergy, asthma and autoimmune diseases. The field of allergen-specific immunotherapy is experiencing exciting and novel developments for the treatment of allergic and autoimmune diseases, and recent insights into the reciprocal regulation and counter-balance between different T-cell subsets is foreseen to facilitate new strategies for immunointervention. This Review highlights current knowledge of immunomodulatory therapies for the manipulation of immune tolerance and highlights recent approaches to improve allergen-specific immunotherapy for the treatment of allergic diseases.

Displaying Fel d1 on virus-like particles prevents reactogenicity despite greatly enhanced immunogenicity: a novel therapy for cat allergy

Allergen-specific desensitization is the only disease-modifying therapy currently available for the treatment of allergies. These therapies require application of allergen over several years and some may induce life-threatening anaphylactic reactions. An ideal vaccine for desensitization should be highly immunogenic and should alleviate allergic symptoms upon few injections while being nonreactogenic. We describe such a vaccine for the treatment of cat allergy, consisting of the major cat allergen Fel d1 coupled to bacteriophage Qβ-derived virus-like particles (Qβ–Fel d1). Qβ–Fel d1 was highly immunogenic, and a single vaccination was sufficient to induce protection against type I allergic reactions. Allergen-specific immunoglobulin G antibodies were shown to be the critical effector molecules and alleviated symptoms by two distinct mechanisms. Although allergen-induced systemic basophil degranulation was inhibited in an FcγRIIb-dependent manner, inhibition of local mast cell degranulation in tissues occurred independently of FcγRIIb. In addition, treatment with Qβ–Fel d1 abolished IgE memory responses upon antigen recall. Despite high immunogenicity, the vaccine was essentially nonreactogenic and vaccination induced neither local nor systemic anaphylactic reactions in sensitized mice. Moreover, Qβ–Fel d1 did not induce degranulation of basophils derived from human volunteers with cat allergies. These data suggest that vaccination with Qβ–Fel d1 may be a safe and effective treatment for cat allergy.

CD-sens: a biological measure of immunological changes stimulated by ASIT

BACKGROUND

Allergen-specific immunotherapy (ASIT) in allergic rhinitis and asthma is the only treatment that effects the long-term development of these diseases. Basophil allergen threshold sensitivity, CD-sens, which is a valuable complement to resource-demanding clinical challenge tests, was used to monitor the initiation of ASIT induced allergen 'blocking activity'.

METHODS

Patients IgE-sensitized to timothy (n = 14) or birch (n = 19) pollen were started on conventional (8-16 weeks) or ultra rush ASIT, respectively, and followed by measurements of CD-sens, allergen binding activity (ABA) and serum IgG4- and IgE-antibody concentrations.

RESULTS

CD-sens decreased during the early phase of ASIT-treatment. In parallel, ABA increased and correlated significantly with the increasing levels of IgG4 antibody concentrations. High dosages of allergen were more effective while mode of dosing up did not seem to matter. No change was seen in basophil reactivity.

CONCLUSION

CD-sens and ABA, in contrast to basophil reactivity, seem to be promising tools to monitor protective immune responses initiated by ASIT.

Mechanisms and treatment of allergic disease in the big picture of regulatory T cells

Various populations of regulatory T (Treg) cells have been shown to play a central role in the maintenance of peripheral homeostasis and the establishment of controlled immune responses. Their identification as key regulators of immunologic processes in peripheral tolerance to allergens has opened an important era in the prevention and treatment of allergic diseases. Both naturally occurring CD4+CD25+ Treg cells and inducible populations of allergen-specific, IL-10-secreting Treg type 1 (T(R)1) cells inhibit allergen-specific effector cells in experimental models. Skewing of allergen-specific effector T cells to a regulatory phenotype appears to be a key event in the development of healthy immune response to allergens and successful outcome in allergen-specific immunotherapy. Forkhead box protein 3-positive CD4+CD25+ Treg cells and T(R)1 cells contribute to the control of allergen-specific immune responses in several major ways, which can be summarized as suppression of dendritic cells that support the generation of effector T cells; suppression of effector T(H)1, T(H)2, and T(H)17 cells; suppression of allergen-specific IgE and induction of IgG4; suppression of mast cells, basophils, and eosinophils; interaction with resident tissue cells and remodeling; and suppression of effector T-cell migration to tissues. Current strategies for drug development and allergen-specific immunotherapy exploit these observations, with the potential for preventive therapies and cure for allergic diseases.

Nature of regulatory T cells in the context of allergic disease

Allergen-specific immunotherapy (SIT) is the cornerstone of the management of allergic diseases, which targets modification of the immunologic response, along with environmental allergen avoidance and pharmacotherapy. SIT is associated with improved tolerance to allergen challenge, with a decrease in immediate-phase and late-phase allergic inflammation. SIT has the potential to prevent development of new sensitizations and progression of allergic rhinitis to asthma. It has a role in cellular and humoral responses in a modified pattern. The ratio of T helper (Th)1 cytokines to Th2 cytokines is increased following SIT, and functional regulatory T cells are induced. Interleukin-10 production by monocytes, macrophages, and B and T cells is increased, as well as expression of transforming growth factor β. SIT is associated with increases in allergen-specific antibodies in IgA, IgG1, and IgG4 isotypes. These blocking-type immunoglobulins, particularly IgG4, may compete with IgE binding to allergen, decreasing the allergen presentation with the high- and low-affinity receptors for IgE (FcεRI and FcεRII, respectively). Additionally, SIT reduces the number of mast cells and eosinophils in the target tissues and release of mediators from these cells.

Effect of sublingual immunotherapy with grass monomeric allergoid on allergen-specific T-cell proliferation and interleukin 10 production

BACKGROUND

Sublingual immunotherapy (SLIT) is safe and efficacious in the treatment of patients with allergic rhinitis. Although favorable clinical effects have been observed with controlled trials as early as a few months since the beginning of treatment, few biological changes induced by SLIT have been demonstrated.

OBJECTIVE

To investigate in grass-allergic patients the effect of a 2-month SLIT regimen, administered with a simplified protocol without up-dosing, on proliferation and production of cytokines characteristic of the regulatory T-cell phenotype (interleukin 10 [IL-10] and transforming growth factor beta [TGF-beta]) by allergen-specific T cells.

METHODS

Patients were recruited to the study in January 2006. SLIT was performed by self-administration and was continued for 60 days from February to April 2006. Eleven grass pollen-allergic patients with seasonal rhinitis were treated daily before the pollen season for 2 months with a modified allergen (monomeric allergoid) derived from a 3-grass pollen extract. Allergen-specific proliferation and production of IL-10 and TGF-beta were measured on peripheral blood mononuclear cells at baseline and treatment end. Tetanus toxoid served as the control antigen.

RESULTS

After SLIT, allergen-specific (P = .002) but not tetanus toxoid-specific proliferation decreased, whereas IL-10 transcription increased (P < .001). TGB-beta transcription was also increased after treatment, although not statistically significantly (P = .06). Changes in proliferation to allergen and in IL-10 transcription were correlated (r = -0.82, P = .003).

CONCLUSIONS

A short-term course of SLIT with modified allergen in grass-allergic patients is associated with the reduction of allergen-specific proliferation and with the up-regulation of the IL-10 regulatory cytokine.

Advances in hymenoptera venom immunotherapy

PURPOSE OF REVIEW

Venom immunotherapy is highly effective treatment, capable of improving health-related quality of life. This overview examines advances in various aspects of this treatment.

RECENT FINDINGS

New findings on the immunological mechanisms of the early and long-term efficacy of venom immunotherapy have been made. The decision to start and then to stop venom immunotherapy is best made on an individual case basis and should take into account medical and other factors, like the influence on patient quality of life. Venoms for use in immunotherapy should be selected according to the geographical distribution of each species and partial cross-reactivity between certain types of venom. Rapid protocols seem to be as safe as slower ones, though the major incidence of bee venom immunotherapy side-effects remains. Patients suffering from mast cell diseases seem to be at greater risk for an adverse reaction during treatment, without influencing its efficacy that much until the immunotherapy is actually ongoing. A number of new strategies for venom immunotherapy, mostly based on genetic engineering, have been described, and so far only a few have been used in humans.

SUMMARY

Although there has been progress in the past few years, much remains to be accomplished.

Patterns of immunoglobulin G responses to egg and peanut allergens are distinct: ovalbumin-specific immunoglobulin responses are ubiquitous, but peanut-specific immunoglobulin responses are up-regulated in peanut allergy

BACKGROUND

The clinical significance of food-specific IgG subclasses in food allergy and tolerance remains unclear. Specific IgG titres are often reported in non-standardized units, which do not allow comparisons between studies or allergens.

OBJECTIVE

To quantify, in absolute units, ovalbumin (OVA)- and peanut-specific IgG levels in children with peanut or egg allergy (active or resolved) and in non-allergic controls. Methods Children aged 1-15 years were recruited. Peanut allergy was diagnosed by convincing history and a 95% predictive level of specific IgE; egg allergy or resolution was confirmed by oral challenge. Serum IgG, IgG1 and IgG4 levels (microg/mL) to OVA and peanut extract were quantified by ELISA.

RESULTS

OVA- and peanut-specific IgG was detected in all subjects. In non-allergic controls (n=18), OVA-specific IgG levels were significantly higher than peanut-specific IgG (median microg/mL IgG=15.9 vs. 2.2, IgG1=1.3 vs. 0.6, IgG4=7.9 vs. 0.7; P<0.01). There were no differences in OVA-specific IgG, IgG1 and IgG4 between egg-allergic (n=40), egg-resolved (n=22) and control (n=18) subjects. In contrast, peanut-specific IgG (median microg/mL IgG=17.0, IgG1=3.3, IgG4=5.2) were significantly higher in peanut-allergic subjects (n=59) compared with controls and with non-peanut-sensitized but egg-allergic subjects (n=26). Overall, the range of IgG4 was greater than IgG1, and IgG4 was the dominant subclass in >60% of all subjects.

CONCLUSION

OVA-specific IgG levels of egg-allergic, egg-resolved or control groups are not distinguishable. Higher peanut-specific IgG levels are associated with clinical allergy, but the range of IgG titres of the allergic and control groups overlapped. Hence, OVA and peanut-specific IgG measurements do not appear to be of diagnostic value. Strong IgG responses to OVA may be a normal physiological response to a protein frequently ingested from infancy, whereas up-regulated IgG responses in peanut allergy may be indicative of a dysregulated immune response to peanut allergens.

Sedimentation field flow fractionation of immunoglobulin A coated polystyrene beads

The amount of immunoglobulin A (IgA) adsorbed on the surface of two different samples of polystyrene (PS) microbeads was evaluated using differential sedimentation field flow fractionation (SdFFF) analyses. For the first time, the SdFFF separations obtained by using, as mobile phase, solutions common to many biochemical procedures and applications have been compared and discussed. Good separation results were achieved in the different carriers, and the SdFFF gave equivalent mass per particle values in all carriers provided that the pH and ionic strength conditions of the eluents were well controlled. The IgA adsorption process onto PS occurred by maintaining unaltered the capacity of the PS-IgA substrate to selectively recognize anti-IgA (aIgA), as proven by elution of the ternary complex PS-IgA-aIgA and from the monitored lack of reaction when the PS-IgA was placed in contact with aIgE.

Signaling through Fc gamma RIII is required for optimal T helper type (Th)2 responses and Th2-mediated airway inflammation

Although inhibitory Fc gamma receptors have been demonstrated to promote mucosal tolerance, the role of activating Fc gamma receptors in modulating T helper type (Th)2-dependent inflammatory responses characteristic of asthma and allergies remains unclear. Here, we demonstrate that signaling via activating Fc gamma receptors in conjunction with Toll-like receptor 4 stimulation modulated cytokine production from bone marrow-derived dendritic cells (DCs) and augmented their ability to promote Th2 responses. Ligation of the low affinity receptor Fc gamma RIII was specifically required for the enhanced Th2 responses, as Fc gamma RIII(-/-) DCs failed to augment Th2-mediated airway inflammation in vivo or induce Th2 differentiation in vitro. Further, Fc gamma RIII(-/-) mice had impaired Th2 cytokine production and exhibited reduced airway inflammation, whereas no defect was found in Fc gamma RI(-/-) mice. The augmentation of Th2 immunity was regulated by interleukin 10 production from the DCs but was distinct and independent of the well-established role of Fc gamma RIII in augmenting antigen presentation. Thus, our studies reveal a novel and specific role for Fc gamma RIII signaling in the regulation of Th cell responses and suggest that in addition to immunoglobulin (Ig)E, antigen-specific IgG also contributes to the pathogenesis of Th2-mediated diseases such as asthma and allergies.

Immunomodulation: the future cure for allergic diseases

Allergies are the result of aberrant immune reactivity against common innocuous environmental proteins (allergens). A pivotal component of allergic pathogenesis is the generation of allergen-specific Th cells with an effector phenotype. These Th cells activate a complex immune cascade that triggers the release of potent mediators and enhances the mobilization of several inflammatory cells types, which in turn elicit the acute allergic reactions and promote the development of chronic inflammation. The current therapies for allergic diseases focus primarily on pharmacological control of symptoms and suppression of inflammation. This approach is beneficial, but not curative, since the underlying immune pathology is not inhibited. In an attempt to develop more effective therapeutic strategies, the scientific interest has been directed toward methods down-modulating the immune mechanisms that initiate and maintain the allergic cascade. Today, the only widely used disease-modifying form of allergy treatment is the specific immunotherapy with allergen extracts. More recently the use of anti-IgE has been approved for patients with allergic asthma. Other immunomodulatory methods being currently explored are the administration of microbial adjuvants that inhibit Th2 reactivity and the design of molecules that interrupt the activity of key allergic cytokines, chemokines, or other Th2 effector mediators.

Mechanisms of allergen-specific immunotherapy

Allergen-specific immunotherapy (SIT) has been used for almost a century as a desensitizing therapy for allergic diseases and represents the only curative and specific method of treatment. Administration of appropriate concentrations of allergen extracts has been shown to be reproducibly effective when patients are carefully selected. The mechanisms by which allergen-SIT has its effects include the modulation of T-cell and B-cell responses and related antibody isotypes as well as effector cells of allergic inflammation, such as eosinophils, basophils, and mast cells. The balance between allergen-specific T-regulatory (Treg) and T(H)2 cells appears to be decisive in the development of allergic and healthy immune responses against allergens. Treg cells consistently represent the dominant subset specific for common environmental allergens in sensitized healthy individuals. In contrast, there is a high frequency of allergen-specific T(H)2 cells in patients with allergy. The induction of a tolerant state in peripheral T cells represents an essential step in allergen-SIT. Peripheral T-cell tolerance is characterized mainly by generation of allergen-specific Treg cells leading to suppressed T-cell proliferation and T(H)1 and T(H)2 cytokine responses against the allergen. This is accompanied by a significant increase in allergen-specific IgG(4), and also IgG(1) and IgA, and a decrease in IgE in the late stage of the disease. In addition, decreased tissue infiltration of mast cells and eosinophils and their mediator release including circulating basophils takes place. Current understanding of mechanisms of allergen-SIT, particularly the role of Treg cells in peripheral tolerance, may enable novel treatment strategies.

Pollen immunotherapy: selection,prevention, and future directions

Pollens are an important cause of allergic rhinitis and asthma. Pollen immunotherapy is effective and potentially curative. It has been shown to prevent new sensitizations, to prevent the development of asthma in children, and to induce long-term benefit. Standardization of allergen extracts is necessary to improve immunotherapy safety and efficacy. Knowledge of the local plant taxonomy and allergen cross-reactivity is important in selecting clinically relevant vaccines. In general, allergenic cross-reactivities correspond to taxonomic relations. Tree and weed species demonstrate variable degrees of cross-reactivity. Most grasses have extensive allergenic cross-reactivity. Mechanism of action continues to be an area of investigation, including the induction of immunoglobulin G blocking antibodies. Sublingual immunotherapy, concurrent anti-immunoglobulin E use, hypoallergic peptides, and DNA vaccines are other promising technologies.

[In vitro allergy testing]

Along with the history, skin tests and provocation tests, in vitro test procedures are essential for the adequate care for patients with allergies. While serological investigations of immediate-type allergic reactions primarily detect allergen-specific IgE antibodies, basophil activation tests with different read-out parameters are available for cellular diagnosis of immediate-type reaction patterns. If clinically necessary, further immunological methods (i. e. immunoblots, lymphocyte transformation tests) can be employed. New options are provided by allergen microarray technology, which makes it possible to determine not only the specific antigenic protein but also to analyze different epitopes.

Production of interleukin-12 by monocytes and interferon-gamma by natural killer cells in allergic patients during rush immunotherapy

BACKGROUND

Allergen specific immunotherapy modifies the immunologic response to allergen exposure; however, the role of cells composing the innate immune system, such as monocytes and natural killer (NK) cells, in this mechanism is still unclear.

OBJECTIVE

To examine the effect of rush immunotherapy (RIT) on early allergen-induced cytokine production by peripheral blood mononuclear cells from treated cat- and birch-allergic patients.

METHODS

Twelve allergic patients received RIT, and another 4 served as controls. Blood samples were taken before the start and after 3 days, 1 week, 3 weeks, and 3 months of RIT. Allergen-induced production of interleukin-12 (IL-12) by monocytes and interferon-gamma (IFN-gamma) by NK cells was evaluated by means of flow cytometry.

RESULTS

Before the start of RIT, allergic patients had significantly lower numbers of IL-12+ monocytes compared with healthy subjects (P = .01). The percentage of IL-12+ monocytes increased after 3 months of RIT (P = .003). In the allergic control group, the proportion of IL-12+ monocytes evaluated after 3 months was not different from baseline and was significantly lower compared with that in the RIT group (P = .005). Before treatment, the percentage of IFN-gamma+ NK cells was lower in allergic patients than in healthy subjects (P = .04). The percentage of IFN-gamma+ NK cells increased after 3 weeks (P = .03) and 3 months (P = .01) of RIT.

CONCLUSIONS

Restoration of the cytokine imbalance by immunotherapy is not only restricted to the cells of the adaptive immune system but also concerns cells composing the innate immune system.

A Cutaneous Allergen Neutralisation Test That Correlates with the Duration of Venom Immunotherapy

BACKGROUND

Despite the well-documented efficacy of Hymenoptera specific immunotherapy (SIT), there is no safe method to reliably characterise the patient level of protection. Only poor correlations between protection and allergen-specific serum immunoglobulins have been found, and a sting challenge is the only means to evaluate the efficacy of immunotherapy. Therefore, we aimed to develop a cutaneous test that measures in vivo neutralisation of the Hymenoptera venom.

MATERIALS AND METHODS

Twenty-four patients with wasp venom allergy were included in the study. Wasp-specific serum IgE, IgG and IgG4 were measured by ImmunoCAP. Dilutions of the individual patient sera were intradermally injected into the forearm. Then, wasp venom extract was injected into these sites to quantitatively assess the formation of wheals and flares.

RESULTS

The results show that during the course of SIT, patient sera gained the capacity to neutralise skin reactions to wasp venom extracts in vivo. The test correlated with the duration of SIT as well as with the concentration of IgG and IgG4.

CONCLUSION

The in vivo neutralisation test may become a promising tool in allergy diagnostics as well as in monitoring the success of SIT in patients undergoing allergen SIT.

The IgE-facilitated allergen binding (FAB) assay: validation of a novel flow-cytometric based method for the detection of inhibitory antibody responses

The IgE-facilitated allergen binding (IgE-FAB) assay represents an in vitro model of facilitated allergen presentation. Allergen-IgE complexes are incubated with an EBV-transformed B cell line and complexes bound to CD23 on the surface of cells are detected by flow cytometry. The addition of serum from patients who have received allergen-specific immunotherapy has been shown previously to inhibit allergen-IgE complex binding to CD23 on B cells. In this study, we describe the characterisation and analytical validation of the grass pollen-specific IgE-FAB assay according to guidelines from the International Conference on Harmonisation. We established the intra- and inter-assay variability of IgE-FAB and have defined the detection limits of this assay. We have also demonstrated assay linearity and robustness. Using the results from a randomised double-blind placebo-controlled trial of grass pollen immunotherapy (n=33), we have defined the clinical sensitivity and specificity of the IgE-FAB assay using ROC curve analysis. In conclusion, the IgE-FAB assay is reproducible, robust, sensitive and a specific method suitable as a tool for monitoring inhibitory antibody function from patients receiving allergen immunotherapy.

Mechanisms of allergen-specific immunotherapy: T-regulatory cells and more

Activation-induced cell death, anergy, or immune response modulation by regulatory T cells (Treg cells) are essential mechanisms of peripheral T-cell tolerance. Genetic predisposition and environmental instructions tune thresholds for the activation of T cells, other inflammatory cells, and resident tissue cells in allergic diseases. Skewing allergen-specific effector T cells to a Treg-cell phenotype seems to be crucial in maintaining a healthy immune response to allergens and successful allergen-specific immunotherapy. The Treg-cell response is characterized by an abolished allergen-specific T-cell proliferation and the suppressed secretion of T-helper 1- and T-helper 2-type cytokines. Suppressed proliferative and cytokine responses against allergens are induced by multiple suppressor factors, including cytokines such as interleukin-10 (IL-10) and transforming growth factor beta (TGF-beta), and cell surface molecules such as cytotoxic T-lymphocyte antigen-4, programmed death-1, and histamine receptor 2. The increased levels of IL-10 and TGF-beta produced by Treg cells potently suppress IgE production while simultaneously increasing the production of noninflammatory isotypes IgG4 and IgA, respectively. In addition, Treg cells directly or indirectly suppress the activity of effector cells of allergic inflammation, such as mast cells, basophils, and eosinophils. In conclusion, peripheral tolerance to allergens is controlled by multiple active suppression mechanisms on T cells, regulation of antibody isotypes, and suppression of effector cells. The application of current knowledge of Treg cells and related mechanisms of peripheral tolerance may soon lead to more rational and safer approaches to the prevention and cure of allergic disease.

Mechanisms of allergen specific immunotherapy--T-cell tolerance and more

Specific immune suppression and induction of tolerance are essential processes in the regulation and circumvention of immune defence. The balance between allergen-specific T-regulatory (Treg) cells and T helper 2 cells appears to be decisive in the development of allergic and healthy immune response against allergens. Treg cells consistently represent the dominant subset specific for common environmental allergens in healthy individuals. In contrast, there is a high frequency of allergen-specific T helper 2 cells in allergic individuals. A decrease in interleukin (IL)-4, IL-5 and IL-13 production by allergen-specific CD4+ T cells due to the induction of peripheral T cell tolerance is the most essential step in allergen-specific immunotherapy (SIT). Suppressed proliferative and cytokine responses against the major allergens are induced by multiple suppressor factors, such as cytokines like IL-10 and transforming growth factor (TGF)-beta and cell surface molecules like cytotoxic T lymphocyte antigen-4, programmed death-1 and histamine receptor 2. There is considerable rationale for targeting T cells to increase efficacy of SIT. Such novel approaches include the use of modified allergens produced using recombinant DNA technology and adjuvants or additional drugs, which may increase the generation of allergen-specific peripheral tolerance. By the application of the recent knowledge in Treg cells and related mechanisms of peripheral tolerance, more rational and safer approaches are awaiting for the future of prevention and cure of allergic diseases.

Differential T cell-mediated regulation of CD23 (Fc epsilonRII) in B cells and follicular dendritic cells

Differences in murine follicular dendritic cells (FDC)-CD23 expression under Th1 vs Th2 conditions prompted the hypothesis that T cells help regulate the phenotype of FDCs. FDCs express CD40, suggesting that T cell-CD40L and lymphokines may be involved in regulating FDC-CD23. To test this, highly enriched FDCs were incubated with CD40L trimer or anti-CD40 to mimic T cell signaling in the presence of IFN-gamma or IL-4. Surface expression of CD23 was determined by flow cytometry, whereas mRNA levels of CD23 and its isoforms CD23a and CD23b were independently measured by quantitative PCR. When FDCs were incubated with either CD40L trimer or agonistic anti-CD40 Ab, the expression of FDC-CD23 was increased both at the mRNA and protein levels. Moreover, engagement of FDC-CD40 enhanced mRNA levels for both CD23a and CD23b isoforms. In addition, IFN-gamma substantially enhanced CD23a and CD23b mRNA levels in CD40-stimulated FDCs. Curiously, IL-4 could also up-regulate FDC-CD23a but not -CD23b. Anti-IFN-gamma dramatically inhibited FDC-CD23 in mice immunized with CFA, whereas anti-IL-4 had only a modest inhibitory effect. In contrast with FDCs, IFN-gamma inhibited surface expression of murine B cell-CD23 as well as mRNA for B cell CD23a and -CD23b, whereas IL-4 dramatically enhanced message for both isoforms as well as protein expression. In short, CD23 was regulated very differently in FDCs and B cells. Previous studies suggest that high levels of FDC-CD23 inhibit IgE production, and this IFN-gamma and CD40L-mediated up-regulation of FDC-CD23 may explain, at least in part, why Th1 responses are associated with low IgE responses in vivo.

Allergy testing: the role of recombinant allergens

Currently, diagnosis of type I allergy is performed using crude allergen extracts, which allow the identification of the allergen-containing source responsible for type I allergic symptoms (e.g., allergic rhino-conjunctivitis, asthma) but not the disease-eliciting molecules. With the introduction of recombinant allergens produced by molecular biology techniques, a large panel of allergenic molecules has become available. The application of these recombinant allergens for in vitro tests has led to new forms of component-resolved diagnosis (CRD) and allows the establishment of a patient's individual reactivity profile. The increasing number of recombinant allergens characterized during the last decade has allowed the development of chip-based allergy tests for simultaneous detection of up to 5000 different allergens and epitopes. The introduction of these recombinant allergen-based tests into clinical practice improves the selection of patients for traditional specific immunotherapy and allows monitoring of the immunological efficacy of specific immunotherapy by measuring allergen-specific IgG antibodies. Besides their diagnostic application, recombinant allergens and hypoallergenic derivatives thereof have also been used as vaccines in clinical trials, and recent results have shown their usefulness for the treatment of type I allergy.

Genetic polymorphisms of major house dust mite allergens

BACKGROUND

Polymorphic sequence substitutions in the major mite allergens can markedly affect immunoglobulin E binding and T cell responses, but there are few studies on environmental isolates from Dermatophagoides pteronyssinus and none for D. farinae.

OBJECTIVE

To determine the sequence variation of the group 1 and 2 allergens from environmental D. pteronyssinus and D. farinae.

METHODS

RNA from each species was isolated from homes in Bangkok and the sequence of Der p 1, Der p 2, Der f 1, and Der f 2 determined from cDNA produced by high fidelity polymerase chain reactions.

RESULTS

The enlarged data set revealed preferred amino acid substitutions in residues 19, 81, and 215 of Der p 1 as well as sporadic changes. Der p 2 showed frequent variations with clusters of amino acid substitutions, but the canonical Der p 2.0101 was not found in any of 17 sequences. Der f 2 showed variants with clusters of substitutions similar to Der p 2 but in different amino acid positions and without any structural concordance. Der f 1 in contrast to the other allergens had few amino acid sequence substitutions.

CONCLUSIONS

The sequence information on variants provides data important for the optimal design of allergen formulations and useful for the genetic engineering and structure-function analyses of the major allergens.

Chemokines in onchocerciasis patients after a single dose of ivermectin

Ivermectin treatment will effectively diminish microfilariae (Mf) of Onchocerca volvulus in the skin of patients, but therapy is associated with adverse host inflammatory responses. To investigate the association of proinflammatory chemokines with the intensity of infection and clinical adverse reactions, chemokine serum levels were measured in patients following ivermectin treatment (100 microg/kg, 150 microg/kg or 200 microg/kg) or placebo. The density of O. volvulus Mf per mg skin decreased by 85%, 97%, 97% and 90% at day 3, at month 3, month 6 and at 1 year post-ivermectin. The cutaneous T cell-attracting chemokine (CTACK/CCL27) was found highly elevated in onchocerciasis patients compared to infection-free European controls (P = 0.0004) and it did not change following ivermectin or placebo to 1 year post-therapy. The chemokine RANTES/CCL5 (regulated on activated and normally T cell-expressed) was similarly high in onchocerciasis patients and infection-free European controls; the RANTES/CCL5 levels did not change following treatment until 6 months post-therapy but were slightly elevated at 1 year post-therapy (P < 0.02). In contrast, the Th2-type chemoattractants, thymus and activation regulated chemokine (TARC/CCL17) and macrophage-derived chemokine (MDC/CCL22), were activated at 3 days post-ivermectin (P < 0.0001) to return to pretreatment or lower levels thereafter. The Th1-type chemoattractants, macrophage inflammatory protein (MIP)-1alpha/CCL3 and MIP-1beta/CCL4 were low before ivermectin treatment, but following clearance of microfilariae of O. volvulus their levels increased from 6 months post-therapy onwards (for both at 12 months post-therapy, P < 0.0001). The adverse reaction scores (RS) in treated patients increased significantly on day 3 (P < 0.02) while it remained unchanged in those who received placebo (P = 0.22); RS interacted with the microfilarial density (P = 0.01), but not with the dose of ivermectin or with the serum levels of MIP-1alpha/CCL3, MIP-1beta/CCL4, TARC/CCL17, MDC/CCL22 and CTACK/CCL27. Our observations suggest that following ivermectin, macrophages as well as memory Th2-type lymphocytes and B cells, attracted and activated by MDC/CCL22, TARC/CCL17 and CTACK/CCL27, may contribute to dermal immune responses and O. volvulus Mf killing and clearance. The transient changes of TARC/CCL17 and MDC/CCL22 were not associated with clinical adverse responses, and the later rise of MIP-1alpha/CCL3 and MIP-1beta/CCL4 showed a reactivation of Type 1 immune responses associated with persistent low levels of O. volvulus microfilariae and an expiring O. volvulus infection.

Immunotherapy of hypersensitivity to hymenoptera venom

Insect sting allergy is a common condition with a risk of life-threatening anaphylaxis. After a severe reaction, the fear of being restung can significantly reduce quality of life. Venom immunotherapy (VIT) is a highly effective treatment of the underlying type I-sensitisation. This review addresses the mechanisms of immune modulation by VIT and outlines current clinical application. Although highly effective in the majority of patients, VIT fails in a few individuals. It can also cause systemic allergic side effects, restricting its application to physicians trained in the treatment of anaphylaxis. This review discusses several new strategies to overcome these problems, which are presently a promising focus of research. These include the use of new adjuvants, of recombinant and genetically engineered venom allergens, as well as vaccination with peptides.