Absence of systemic immunologic changes during dose build-up phase and early maintenance period in effective specific sublingual immunotherapy in children

Specific immunoglobulin G4 correlates with Th2 cytokine reduction in patients with allergic asthma treated by Dermatophagoides pteronyssinus subcutaneous immunotherapy

Background

The modulations of lymphocyte subsets and cytokine production due to subcutaneous allergen immunotherapy (SCIT) are not fully clarified.

Objective

We investigated the changes in T-lymphocyte subsets and serum Dermatophagoides pteronyssinus-specific immunoglobulin G4 (Der-p sIgG4), as well as cytokine production during Der-p SCIT, in patients with allergic asthma.

Methods

This study involved 20 patients with allergic asthma who were receiving 156-week Der-p SCIT and 20 patients without SCIT (non-SCIT). We measured symptom and medication scores (SMS), serum Der-p sIgG4 levels, CD4⁺CD25⁺Foxp3⁺ T regulatory (Treg), CD4⁺IL-4^-IFN-γ⁺ T-helper (Th) 1, and CD4⁺IL-4⁺IFN-γ^- Th2 lymphocyte percentages in peripheral blood mononuclear cells (PBMCs) with/without Der-p extract stimulation at weeks 0, 4, 12, 16, 52, 104, and 156. Cytokine release inhibition assays were performed by incubation with serum from SCIT and non-SCIT patients, Der-p allergen, and PBMCs. Levels of interleukin (IL)-4, IL-5, IL-10, IL-13, IL-17, interferon (IFN)-γ, tumor necrosis factor (TNF)-α, and transforming growth factor (TGF)-β1 were evaluated in supernatant.

Results

We found that SCIT patients had significantly lower SMS after week 52. Der-p sIgG4 levels in SCIT patients significantly increased at week 16 compared with non-SCIT subjects. CD4⁺IL-4⁺IFN-γ^- Th2% in SCIT patients showed a significant decrease from weeks 104-156 compared with week 0, while no change was observed in CD4⁺CD25⁺Foxp3⁺ Treg and CD4⁺IL-4^-IFN-γ⁺ Th1 percentages. IL-5, IL-13, IL-4, IL-17, and TNF-α levels in supernatant of PBMCs cultured with serum of SCIT patients after 16 weeks showed significant lower levels compared with non-SCIT patients, and showed significant reverse associations with Der-p sIgG4 levels.

Conclusion

SCIT induced Dep-p sIgG4 may be involved in downregulating Th2 cytokine production in Der-p allergic asthma patients.

Artemisia annua-sublingual immunotherapy for seasonal allergic rhinitis: A randomized controlled trial

BACKGROUND

Artemisia annua is an important autumnal pollen allergen for seasonal allergic rhinitis (SAR) in northern China. To date, no study has investigated allergen immunotherapy with A annua. We aimed to investigate the efficacy and mechanisms underlying A annua-sublingual immunotherapy (SLIT).

METHODS

This was a randomized, double-blind, placebo-controlled phase III clinical trial involving 71 SAR patients, randomized to SLIT with A annua extract (n = 47) or placebo (n = 24) for 32 weeks. Total nasal symptom score (TNSS; primary clinical end point) was evaluated at baseline (peak pollen phase (PPP) in the previous year), initiation of A annua-SLIT, 1st PPP during SLIT, end of SLIT and 2nd PPP during follow-up. Blood samples and nasal secretions were collected at beginning and after SLIT for assessment of T cells and inflammatory mediators. Safety was assessed according to adverse events (AEs) reported.

RESULTS

Artemisia annua-SLIT significantly reduced TNSS to a greater level from baseline (from 9.45 ± 1.68 to 6.16 ± 2.27) than placebo (from 9.29 ± 2.09 to 9.05 ± 2.40) at the 1st PPP (P < .001) and sustained the improvement in symptoms throughout to the 2nd PPP. Preseasonal A annua-SLIT for 16 weeks significantly decreased Th2 cells, increased nTreg and Tr1 cells in blood; and increased cystatin 1 (CST1) in nasal secretion after 16 and 32 weeks compared with pretreatment. Overall, 17/47 patients experienced mild local AEs and 2 patients mild systemic AEs, after A annua-SLIT.

CONCLUSION

Artemisia annua-SLIT is an efficacious and safe treatment in patients with A annua SAR.

Recombinant allergens for immunotherapy: state of the art

PURPOSE OF REVIEW

More than 30 years ago, the first molecular structures of allergens were elucidated and defined recombinant allergens became available. We review the state of the art regarding molecular AIT with the goal to understand why progress in this field has been slow, although there is huge potential for treatment and allergen-specific prevention.

RECENT FINDINGS

On the basis of allergen structures, several AIT strategies have been developed and were advanced into clinical evaluation. In clinical AIT trials, promising results were obtained with recombinant and synthetic allergen derivatives inducing allergen-specific IgG antibodies, which interfered with allergen recognition by IgE whereas clinical efficacy could not yet be demonstrated for approaches targeting only allergen-specific T-cell responses. Available data suggest that molecular AIT strategies have many advantages over allergen extract-based AIT.

SUMMARY

Clinical studies indicate that recombinant allergen-based AIT vaccines, which are superior to existing allergen extract-based AIT can be developed for respiratory, food and venom allergy. Allergen-specific preventive strategies based on recombinant allergen-based vaccine approaches and induction of T-cell tolerance are on the horizon and hold promise that allergy can be prevented. However, progress is limited by lack of resources needed for clinical studies, which are necessary for the development of these innovative strategies.

Induction of IgG2 and IgG4 B-cell memory following sublingual immunotherapy for ryegrass pollen allergy

BACKGROUND

While treatment for atopic rhinitis is aimed mostly to relieve symptoms, only allergen-specific immunotherapy (AIT) is targeted to modify the natural history of allergic diseases. This results in sustained clinical tolerance, even when treatment has stopped. The immunomodulatory effects of AIT are attributed mainly to increased regulatory T-cell function and increased allergen-specific IgG₄ , yet little is known about the effect on the memory B-cell compartment.

OBJECTIVE

We aimed to examine the effects of AIT on the IgE- and IgG subclass-expressing memory B cells.

METHODS

We recruited 29 patients with atopic seasonal rhinoconjunctivitis and performed a longitudinal analysis of the peripheral immune compartment before, during, and after sublingual immunotherapy (SLIT) for allergy to temperate grass pollen, predominantly to ryegrass pollen (RGP; Lolium perenne). Using flow cytometry on peripheral blood mononuclear cells and serum immunoassays, we analyzed the effects of a 4 months preseasonal treatment regimen comprising two or three courses in consecutive years on circulating IgE⁺ and IgG⁺ memory B cells and allergen-specific Ig levels.

RESULTS

SLIT increased RGP-specific serum IgG₂ and IgG₄ , as well as the frequencies of IgG₂ ⁺ and IgG₄ ⁺ memory B cells, whereas no effect was observed on the IgE⁺ memory B-cell compartment. Furthermore, SLIT enhanced proportions of regulatory T cells specific to RGP. These changes were associated with clinical improvement.

CONCLUSION

Our data provide evidence for immunological effects of SLIT on B-cell memory. Skewing responses toward IgG₂ and IgG₄ subclasses might be a mechanism to suppress IgE-mediated allergic responses.

Dust mite allergen-specific immunotherapy increases IL4 DNA methylation and induces Der p-specific T cell tolerance in children with allergic asthma

Allergen-specific immunotherapy (allergen-SIT) is a highly effective treatment for children with allergic asthma (AA), an immune-mediated chronic disease leading to bronchial muscle hypertrophy and airway obstruction in response to specific allergens. T helper cells and secreted cytokines play important roles in the pathogenesis of asthma, and epigenetic modulation controls genes important for T cell development and cytokine expression. This study evaluated T helper cell-secreted cytokines and DNA methylation patterns in children treated with Dermatophagoides pteronyssinus (Der p) allergen-SIT. Our results showed that after Der p challenge, peripheral blood mononuclear cells (PBMCs) from the SIT group, compared with the non-SIT AA group, produced lower levels of IL-4, IL-5 and IL-2. The SIT group, compared with the AA group, exhibited decreased sensitivity to the Der p allergen, concurrent with IL-4 down-modulation due to increased promoter DNA methylation, as estimated in PBMCs. Our results showed that SIT decreased IL-4 and IL-5, and inhibited T cell proliferation, by inhibiting IL-2 production after the specific allergen challenge. These results suggest that decreased IL-2 production and increased IL-4 cytokine promoter methylation is a potential mechanism of Der p-specific allergen desensitization immunotherapy.

Biomarkers for Allergen Immunotherapy: A "Panoromic" View

Biomarkers (BMKs) are biological parameters that can be measured to predict or monitor disease severity or treatment efficacy. The induction of regulatory dendritic cells (DCs) concomitantly with a downregulation of proallergic DC2s (ie, DCs supporting the differentiation of T-helper lymphocyte type 2 cells) in the blood of patients allergic to grass pollen has been correlated with the early onset of allergen immunotherapy efficacy. The combined use of omics technologies to compare biological samples from clinical responders and nonresponders is being implemented in the context of nonhypothesis-driven approaches. Such comprehensive "panoromic" strategies help identify completely novel candidate BMKs, to be subsequently validated as companion diagnostics in large-scale clinical trials.

Preventive sublingual immunotherapy in preschool children: first evidence for safety and pro-tolerogenic effects

BACKGROUND

Prevention of new IgE sensitizations has been described during allergen-specific immunotherapy. However, prospective data using a preventive approach in very young children who would benefit most are missing. We initiated a prospective pilot study investigating the safety, immunomodulatory, and sensitization-preventive effect of sublingual immunotherapy (SLIT) in mono/oligoclonally sensitized, clinically asymptomatic children 2-5 yr of age.

METHODS

In this double-blinded, randomized, placebo-controlled pilot study, 31 mono-/oligosensitized children to house-dust mite or grass pollen were included. SLIT with the respective source (n = 15) or placebo (n = 16) was applied. After dose-up-phase therapy was continued for 2 yr. Parents recorded clinical events, vaccinations, and drug intake in a diary. Skin prick testing and specific IgE and IgG measurements were recorded at baseline, 12 and 24 months. At the same time, allergen-specific proliferation and IL10- and TGFβ-dependent Treg function were measured.

RESULTS

Preventive application of SLIT in young children was safe (no relevant side effects in 21,170 single applications). After 12 and 24 months of treatment, the rate of allergen-specific sensitization (specific IgE and SPT reactivity) was comparable in the treatment and the placebo group. However, verum-treated patients displayed a significant up-regulation of allergen-specific IgG (p < 0.05). Furthermore, IL10-dependent inhibition (p < 0.05) was observed in vitro in the treatment group but not in the placebo group.

CONCLUSION

Preventive SLIT is safe in children 2-5 yr of age and induces regulatory mechanisms involving allergen-specific IgG and IL10. Based on this pilot study, large-scale trials will need to investigate the modulation of sensitization and clinically relevant allergy.

Allergen-specific CD4+ T cell responses in peripheral blood do not predict the early onset of clinical efficacy during grass pollen sublingual immunotherapy

BACKGROUND

Surrogate biomarkers of efficacy are needed in support of allergen-specific immunotherapy.

OBJECTIVE

The aim of this study was to relate changes in peripheral CD4(+) T cell responses to clinical efficacy during sublingual immunotherapy (SLIT).

METHODS

Allergen-specific CD4(+) T cell responses were assessed in peripheral blood mononuclear cells (PBMCs) from 89 grass pollen-allergic individuals enrolled in a double-blind placebo-controlled SLIT study conducted in an allergen exposure chamber (ClinicalTrials.gov NCT00619827). Surface phenotype, proliferative responses, cytokine production and gene expression were analysed in coded samples at baseline, and after 2 and 4 months of SLIT, in PBMCs after in vitro allergen stimulation or among MHC class II/peptide (pMHCII)-tetramer-positive CD4(+) T cells.

RESULTS

SLIT induced a 29.3% improvement of the average rhinoconjunctivitis total symptom score in the active group, when compared to the placebo group. In parallel, only minor changes in proportions of CD4(+) T cells expressing Th1 (CCR5(+), CXCR3(+)), Th2 (CRTh2(+), CCR4(+)) and Treg (CD25(+), CD127(-), Foxp3(+)) markers were detected. A down-regulation of IL-4 and IL-10 gene expression and IL-10 secretion (P < 0.001) were observed, as well as a decrease in the frequency of potential "pro-allergic" CD27(-) Th2 cells from patients receiving active tablets (P < 0.001), but without any correlation with clinical benefit. pMHCII-tetramer analyses failed to document any major impact in both numbers and polarization of circulating Phl p 1- and Phl p 5-specific CD4(+) T cells, confirming that early clinical improvement during SLIT is not associated with dramatic alterations in T lymphocyte responses.

CONCLUSION & CLINICAL RELEVANCE

Changes in patterns of peripheral CD4(+) T cells are not markers for the early onset of efficacy during SLIT.

Update on immune mechanisms associated with sublingual immunotherapy: practical implications for the clinician

Sublingual immunotherapy (SLIT) is established as a safe and efficacious treatment for patients with type I respiratory allergies. The ability of SLIT to elicit antigen (allergen)-specific tolerance is linked to the peculiar biology of oral antigen-presenting cells. In the absence of danger signals, Langerhans cells, myeloid dendritic cells, and macrophages located in oral tissues, tonsils, and draining cervical lymph nodes are biased toward the induction of T(H)1 and IL-10-producing CD4(+) regulatory T cells, thus supporting tolerance as opposed to inflammation. Sublingual administration does not lead to any detectable systemic exposure of intact allergens nor to IgE neosensitization. Oral tissues contain limited numbers of mast cells located in submucosal areas, thereby explaining the well-established safety profile of SLIT, with mostly local but rare systemic reactions. The induction of CD4(+) regulatory T cells and blocking anti-inflammatory IgGs or IgAs are considered important for tolerance induction after SLIT. Specific molecular signatures associated with tolerogenic dendritic cells were recently reported during the onset of SLIT efficacy in the peripheral blood of patients exhibiting clinical benefit. Collectively, these observations confirm the induction of strong allergen-specific suppressive/tolerogenic immune responses during SLIT and pave the ground for the identification of biomarkers of efficacy. Practical implications of this emerging scientific knowledge are presented (1) to support the rational design of second-generation sublingual vaccines based on purified allergens, vector systems and/or adjuvants and (2) to help the clinician in decision making during his/her practice.

Treatment of seasonal allergic rhinoconjunctivitis with a once-daily SQ-standardized grass allergy immunotherapy tablet

OBJECTIVES

Specific immunotherapy with the grass allergy immunotherapy tablet (AIT) has been developed as an effective, well tolerated, and convenient treatment for grass pollen induced seasonal allergic rhinoconjunctivitis (ARC). Six phase II/III randomized, placebo-controlled trials with the duration of a single grass pollen season of treatment using the SQ-standardized grass AIT, Grazax (Phleum pratense, 75,000 SQ-T/2,800 BAU, ALK, Denmark), have been published previously. This review compares results from these trials.

METHODS

As outcome measures and methods of assessing them were similar across the trials, we have summarized the main efficacy findings (Total Combined Score [TCS], average daily rhinoconjunctivitis symptom and medication scores, percentage of well days, quality of life scores) during a single season of treatment with grass AIT in adults and children with seasonal ARC.

RESULTS

The results of the European and North American trials were similar. Compared with the placebo group, who received symptomatic medications only, treatment with grass AIT resulted in fewer rhinoconjunctivitis symptoms, a lower intake of symptomatic medication, better patient self-rated quality of life and a greater percentage of well days during the entire grass pollen season. The data indicate that grass AIT treatment is equally effective in adults and children; the measured effect varies with pollen exposure, but is comparable across regions and continents, with a consistent difference compared with placebo in TCS that was above 20% for all trials. Local adverse events were experienced by the majority of patients. These reactions were generally mild to moderate in severity and transient in duration. Systemic adverse events were rare.

CONCLUSIONS

This review confirms SQ-standardized grass AIT as a suitable therapeutic option for seasonal use in patients aged 5 years or older with grass pollen induced ARC.

Responses of CD4(+) CD25(+) Foxp3(+) and IL-10-secreting type I T regulatory cells to cluster-specific immunotherapy for allergic rhinitis in children

We investigated the effects of cluster specific immunotherapy (SIT) with Dermatophagoides pteronyssinus (Der p) on CD4(+) CD25(+) Foxp3(+) Treg cells and IL-10-secreting type I T regulatory (Tr1) cells in Der p-sensitized children with allergic rhinitis (AR). We performed a prospective randomized study involving 46 children (aged 8-13 yr), of whom 25 children received Der p-SIT + pharmacotherapy and 21 received only pharmacotherapy, over a period of 1 yr. Prior to and at end of treatment, CD4(+) CD25(+) Foxp3(+) Treg cells and allergen-specific IL-10(+) IL-4(-) , IFN-γ(+) IL-4(-) , and IL-4(+) IFN-γ-CD4(+) T cells were measured by flow cytometry. Similarly, IL-4, IFN-γ, and IL-10 in supernatants from allergen-stimulated peripheral blood mononuclear cell (PBMC) cultures were measured by ELISA, and the suppressive effect of CD4(+) CD25(high) T cells on cell proliferation and cytokine release was estimated from both groups. Allergen-specific serum IgE and IgG4 were also assessed at the beginning and end of treatment by RAST and ELISA, respectively. The levels of allergen-specific Tr1 cells, IgG4, and allergen-induced IL-10 synthesis from PBMC cultures were significantly increased after SIT for 1 yr compared with baseline levels (p < 0.001 for all), with significant correlation between increased levels of Tr1 cells and improvements in nasal symptoms (r = 0.48, p < 0.05). In contrast, the levels of CD4(+) CD25(+) Foxp3(+) T cells, allergen-specific Th1 and Th2 cells, the production of IL-4 and IFN-γ, and the function of CD4(+) CD25(high) T cells were not altered in either group at the end of treatment. These data suggest that the up-regulation of Tr1 cells may play an important role in SIT and be a useful marker of successful SIT in AR patients.

Local immunological mechanisms of sublingual immunotherapy

PURPOSE OF REVIEW

To summarize novel insights into the immunological mechanisms of sublingual immunotherapy (SLIT). Within the recent decades, several alternative noninvasive allergen application strategies have been investigated in allergen-specific immunotherapy (AIT), of which intra-oral allergen application to sublingual mucosa has been proven to be well tolerated and effective.

RECENT FINDINGS

To date, SLIT is widely accepted by most allergists as an alternative option to conventional subcutaneous immunotherapy (SCIT). Although detailed immunological mechanisms remain to be elucidated, much scientific effort has been made to shed some light on local and systemic immunological responses to SLIT in mice as well as humans. Only a few studies focused on the detailed mechanisms following allergen application to the oral mucosa as part of the sophisticated mucosal immunological network. Within this network, the pro-tolerogenic properties of local antigen-presenting cells (APCs) such as dendritic cells - which are able to enforce tolerogenic mechanisms and to induce T-cell immune responses - play a central role. Further on, basic research focused not only on the immune response in nasal and bronchial mucosa but also on the systemic T-cell immune response.

SUMMARY

Thus, much exiting data have been published providing a better understanding of immunological features of SLIT but far more investigations are necessary to uncover further exciting details on the key mechanisms of SLIT.

Specific immunotherapy in children: the evidence

Specific immunotherapy (SIT) is the only treatment able to not only act on the symptoms of allergy but also act on the causes. At present, SIT may be administered in two forms: subcutaneous (SCIT) and sublingual immunotherapy (SLIT). SCIT represents the standard modality of treatment while SLIT has recently been introduced into clinical practice and today represents an accepted alternative to SCIT. The main advantages of SIT that are lacking with drug treatment are long-lasting clinical effects and alteration of the natural course of the disease. This prevents the new onset of asthma in patients with allergic rhinitis and the onset of new sensitizations. The mechanism of action of both routes is similar; they modify peripheral and mucosal Th2-responses into a prevalent Th1-polarization with subsequent reduction of the allergic inflammatory reaction. Both have long-term effects for years after they have been discontinued, although for SLIT these evidences are insufficient. To date several guidelines have defined indications, controindications, side-effects, and clinical aspect for SCIT and SLIT. New forms of immunotherapy, allergen products and approaches to food allergy and atopic eczema represents the future of SIT.

Mechanisms of immunotherapy to aeroallergens

Allergen immunotherapy is allergen-specific, allergen dose- and time-dependent and is associated with long-term clinical and immunological tolerance that persists for years after discontinuation. Successful immunotherapy is accompanied by the suppression of numbers of T-helper 2 (Th2) effector cells, eosinophils, basophils, c-kit+mast cells and neutrophils infiltration in target organs, induction of IL-10 and/or TGF-β+Treg cells and increases in 'protective' non-inflammatory blocking antibodies, particularly IgG4 and IgA2 subclasses with inhibitory activity. These events are accompanied by a reduction and/or a redirection of underlying antigen-specific Th2-type T cell-driven hypersensitivity to the allergen(s) used for therapy. This suppression occurs within weeks or months as a consequence of the appearance of a population of regulatory T cells that exert their effects by mechanisms involving cell-cell contact, but also by the release of cytokines such as IL-10 (increases IgG4) and TGF-β (increases specific IgA). The more delayed-in-time appearance of antigen-specific T-helper 1 responses and alternative mechanisms such as Th2 cell anergy and/or apoptosis may also be involved. The mechanisms of sublingual immunotherapy are similar to those following a subcutaneous administration of allergen, whereas it is likely that additional events following antigen presentation in the sublingual mucosa and regional lymph nodes are involved. These insights have resulted in novel approaches and portend future biomarkers that may be surrogate or predictive of the clinical response to treatment.

Effect of sublingual immunotherapy on level of cytokines in PBMCs of patients with allergic asthma

This study examined the possible mechanism of sublingual immunotherapy (SLIT) in the treatment of allergic asthma. Forty asthma patients allergic to dust mite were enrolled. They received SLIT with dermatophagoides farinae (Der. f) drops for one year. Thirty healthy subjects served as controls. The levels of IL-4 and IFN-γ of peripheral blood mononuclear cells (PBMCs) were determined in allergic asthma patients before and after the SLIT as well as the healthy subjects. The results showed that the level of IL-4 was substantially increased and that of IFN-γ remarkably decreased in the patients before the SLIT as compared with those in the healthy subjects (P<0.05). After the SLIT, the level of IL-4 was significantly reduced and that of IFN-γ elevated in these allergic asthma patients. It was concluded that sublingual immunotherapy is effective for patients with allergic asthma. And it may work by regulating the balance of Th1/Th2 through changing the expression of IL-4 and IFN-γ in PBMCs.

Sublingual immunotherapy in asthma does not influence lymphocyte sensitivity to Fas stimulation

BACKGROUND

The resistance of T lymphocytes to Fas-mediated apoptosis is an important feature of atopic asthma. The only effective causative treatment of atopic diseases is immunotherapy. Clinical efficacy of sublingual immunotherapy (SLIT) has been already proven, but there is still limited number of studies on its influence on lymphocytes function.

OBJECTIVES

The aim of the study was to evaluate whether SLIT could restore the sensitivity of asthmatic T cells to undergo Fas-mediated apoptosis.

MATERIAL AND METHODS

Peripheral blood was collected from 12 patients aged 8 ±2 years suffering from atopic asthma and undergoing sublingual specific immunotherapy. To evaluate sensitivity to Fas-mediated apoptosis, the blood was transmitted to sterile tubes and mixed with purified monoclonal antibody anti-CD95. After incubation, leukocytes were stained with Annexin V, propidium iodide, and monoclonal antibody against CD2 conjugated with phycoerythrin-cyanin 5.1, and then analyzed with flow cytometry. The procedure was repeated for each patient after 12 months of SLIT. -

RESULTS

Stimulation with anti-CD95 of T lymphocytes from patients with atopic asthma before treatment increased the number of early apoptotic cells (from 19.5 ±16.7% before stimulation to 26.6 ±16.7% Annexin V positive cells after stimulation). After one year of SLIT anti-CD95 still caused an increase of the early apoptotic cells ratio in the lymphocyte population (from 12.4 ±7.4% before stimulation to 24.7 ±15.4% Annexin V positive T cells after CD95 stimulation). Although an increasing trend could be observed, differences between the analyzed groups were not statistically significant.

CONCLUSIONS

A year of SLIT does not change the sensitivity of T lymphocytes from peripheral blood of children suffering from atopic asthma to Fas-mediated apoptosis.

Immunological effects of sublingual immunotherapy: clinical efficacy is associated with modulation of programmed cell death ligand 1, IL-10, and IgG4

Sublingual immunotherapy (SLIT) is an alternate route of administration of allergen-specific immunotherapy with an improved safety profile; to clarify the immune mechanisms elicited by this therapy, we analyzed the clinical and immunologic effects of SLIT in patients with a clinical history of ragweed sensitization. To analyze possible difference among immunotherapeutic protocols, we also compared patients receiving preseasonal, seasonal, or prolonged sublingual therapy (≥ 3 y); patients receiving symptomatic therapy alone were enrolled as well in the study. Clinical and immunological parameters were measured twice in and out of the pollination period. Clinical benefits, as measured by the visual analog scale for symptoms and for use of drugs, were evident in all three groups of individuals receiving immunotherapy, but were significantly better in patients undergoing prolonged SLIT. Immunologically, SLIT resulted in increased IL-10 production, programmed cell death ligand 1 expression, and concentration of allergen-specific IgG4, as well as in the reduction of CD80 and CD86 expression and IL-4 production. SLIT, thus, is associated with modulation of programmed cell death ligand 1 expression and IL-10 synthesis and favors the production of allergen-specific IgG4. These effects are evident from the first pollen season, independently from therapeutic regimen (preseasonal or seasonal) even if a prolonged treatment is necessary to obtain full clinical efficacy. A more detailed understanding of the interaction of allergen and APCs within the oral mucosa will allow improved targeting of allergy vaccine.

Sublingual immunotherapy for Alternaria-induced allergic rhinitis: a randomized placebo-controlled trial

BACKGROUND

Respiratory allergy due to Alternaria is a relevant clinical problem, and specific immunotherapy may represent a viable treatment option. Sublingual immunotherapy (SLIT) is safe and effective, but data for Alternaria are lacking.

OBJECTIVE

To assess the efficacy of standardized SLIT in patients sensitized to Alternaria in a randomized, prospective, double-blind, placebo-controlled trial.

METHODS

Patients with rhinitis with or without intermittent asthma and ascertained allergy to Alternaria were enrolled. After a baseline season, SLIT or matched placebo was given for 10 months. Symptoms and rescue medication intake were recorded on diary cards between June and October. Skin prick testing was performed and specific IgE, IgG4, and precipitin levels were measured at baseline and at the end of the study.

RESULTS

Twenty-seven patients (age range, 14-42 years) were randomized, and 26 completed the study. The baseline characteristics were homogeneous in the 2 groups. After treatment, patients receiving SLIT had a significant improvement in symptoms and a reduction in medication intake vs placebo and vs the run-in season, whereas no change was seen in the placebo group. Skin prick test reactivity significantly decreased only in the SLIT group. No change was seen in specific IgG4 levels in the 2 groups, whereas Alt a 1 specific IgE levels significantly increased in the active group. One patient in the active group reported oral itching and conjunctivitis at the beginning of treatment.

CONCLUSION

SLIT seems effective and safe and may represent a valuable therapeutic option in respiratory allergy due to Alternaria.

Certainties and doubts about sublingual and oral immunotherapy in children

PURPOSE OF REVIEW

Sublingual (SLIT) and oral immunotherapy (OIT) are two variants of immunotherapy that might be especially of interest for children. After adult studies, lately many trials in children are published. However, the quality of published material varies. In the present review we analyze paediatric SLIT publications from the past 2 years in the light of a new system of evaluation of quality of evidence, the grading of recommendations assessment, development and evaluation system.

RECENT FINDINGS

High quality evidence in children: high-dose daily grass SLIT reduces symptoms and medication use; low-dose pollen SLIT reduces the development of new sensitizations. Low-dose SLIT reduces symptoms and medication in mild-moderate atopic dermatitis. Latex SLIT for 3 years results in a negative glove test. The evidence for the effectiveness of SLIT for seasonal and perennial asthma is still of moderate-low quality, as is the evidence for asthma prevention. Too high dose of mite SLIT seems ineffective for asthma. Oral allergen immunotherapy is promising for some food allergies. Some definite immunological changes are seen with SLIT; facilitated antibody presentation and IL-17 might correlate with efficacy.

SUMMARY

Even after a hundred years of immunotherapy, it is still an ever changing field with SLIT and OIT making fast progress.

T-cell responses induced by allergen-specific immunotherapy

Allergen-specific immunotherapy is recognized as a highly effective practice in the treatment of patients with severe allergic rhinitis and/or asthma and is recommended by World Health Organization as an integrated part of allergy management strategy. Several studies have shown that allergen-specific immunotherapy, based on the administration of increasing doses of allergen, achieves a hyposensitization and reduces both early and late responses occurring during the natural exposure to the allergen itself. This is the unique antigen-specific immunomodulatory treatment in current use for human diseases. Successful immunotherapy is associated with reductions in symptoms and medication scores and improved quality of life. After interruption it usually confers long-term remission of symptoms and prevents the onset of new sensitizations in children up to a number of years. Subcutaneous immunotherapy usually suppresses the allergen-induced late response in target organs, likely due to the reduction of the infiltration of T cells, eosinophils, basophils, mast cells and neutrophils. In addition to the reduction of cells of allergic inflammation, immunotherapy also decreases inflammatory mediators at the site of allergen exposure. This review provides an update on the immunological T cell responses induced by conventional subcutaneous and sublingual immunotherapy, and gives a unifying view to reconciling the old dualism between immunoredirecting and immunoregulating mechanisms.

Clinical efficacy and immunological mechanisms of sublingual and subcutaneous immunotherapy in asthmatic/rhinitis children sensitized to house dust mite: an open randomized controlled trial

BACKGROUND

In children, the clinical efficacy and immunological mechanisms of sublingual immunotherapy (SLIT) compared with subcutaneous immunotherapy (SCIT) is still to be elucidated.

OBJECTIVES

To compare SLIT, SCIT and pharmacotherapy in relation to clinical efficacy and immunological mechanisms that govern its effect in asthmatic/rhinitis children who were sensitized to house dust mite (HDM).

METHODS

In this single centre, prospective, randomized, controlled, open labelled, three parallel group trial, 48 patients mono-sensitized to HDM were randomized to receive either SLIT (n=16), SCIT (n=16) or pharmacotherapy alone (n=16). Symptom, medication and visual analogue score (VAS) were collected and bronchial-nasal hyper-reactivity, skin prick tests, total-specific IgE were performed at baseline and 12 months after treatment. In addition, peripheral blood mononuclear cells were cultured with recombinant Der p 1 and Bet v 1 extracts and allergen-specific IL-4, IL-5, IL-13, IFN-gamma, IL-10, and TGF-beta secretions were measured.

RESULTS

SLIT and SCIT demonstrated a significant reduction of total rhinitis and asthma symptom score, total medication score, VAS and skin reactivity to HDM (P<0.05) when compared with pharmacotherapy. A significant reduction of serum-specific HDM-IgE in SCIT and SLIT were observed. Moreover, titrated nasal provocative dose significantly increased in both immunotherapy groups when compared with the pharmacotherapy group. No adverse effects were reported in SLIT, while two patients demonstrated serious adverse events in SCIT. After 1 year of treatment, Der p 1-driven IL-10 significantly increased in SLIT compared with pharmacotherapy, whereas Bet v 1-driven TGF-beta (negative control) increased significantly in SLIT only. No changes were observed for Th1-Th2 cytokines.

CONCLUSION

Both SLIT and SCIT demonstrated clinical improvement compared with pharmacotherapy in asthma/rhinitis children sensitized to HDM.

Elispot and Elisa Assessment of Interferon-Gamma after Sublingual Immunotherapy

Allergic rhinitis (AR) is characterized by a Th2 polarized immune response, and specific immunotherapy modifies this arrangement, restoring a physiologic Th1 profile. Sublingual immunotherapy (SLIT) is widely prescribed. The aim of the study is to evaluate two different methods for assessing IFN-γ, namely ELISPOT and ELISA, before and after a pre-seasonal SLIT course as marker for Th1 response. Thirty-eight AR patients with pollen allergy assumed pre-seasonal SLIT for 3 months. Patients' blood samples for assessing IFN-γ serum levels were collected before initiating SLIT (baseline – T0), after 3 months pre-seasonal SLIT course (T1), and three months after completion of SLIT (T2). IFN-γ-specific producing cells, after allergen stimulation, were assessed by cytokine ELISPOT at the same time points. IFN-γ-specific producing cells significantly increased after SLIT both at T1 and T2 (p=0.0002). On the contrary, ELISA assessment did not reveal an increase in IFN-γ serum levels at any time point. In conclusion, these results demonstrate that ELISA assessment of serum IFN-γ is not suitable for identifying an early response.

Sublingual Immunotherapy Affects Specific Antibody and TGF-β Serum Levels in Patients with Allergic Rhinitis

Allergic rhinitis (AR) is characterized by Th2 polarized immune response, such as increased IL-4 and reduced IFN-γ production. Sublingual allergen-specific immunotherapy (SLIT) induces several immunological changes, most of which are still little known. The aim of this study is firstly to investigate the changes of allergen-specific IgE, IgG, IgG4, and IgA serum levels after SLIT. Secondly, this study aims at relating immunoglobulin (Ig) values with some Th1-, Th2-, and Treg-dependent cytokines. Twenty-three patients with pollen-induced AR were enrolled, and they assumed two pre-seasonal SLIT courses for 2 years. Serum allergen-specific IgE, IgG, IgG4 and IgA levels were determined by ELISA method at baseline and after each SLIT course. Serum IL-4, IFN-γ, IL-10, and TGF-β levels were also assessed. Allergen-specific IgE, IgG, IgG4, and IgA serum levels significantly increased after SLIT. Serum TGF-β significantly increased after SLIT. There was a significant correlation between IgA and TGF-β, both after the first and the second SLIT course. In conclusion, the present study provides the first evidence that pollen SLIT significantly affects Ig production, mainly concerning IgA; and IgA increase is related with TGF-β production. Moreover, this is the first study that measured Ig classes by using a quantitative method.

House dust mite sublingual immunotherapy: the role for transforming growth factor-beta and functional regulatory T cells

RATIONALE

Sublingual allergen-specific immunotherapy is gaining popularity for treatment of allergic diseases, but underlying immunological mechanisms are unresolved.

OBJECTIVES

To perform detailed immunological investigation of sublingual house dust mite (HDM) immunotherapy.

METHODS

A 12-month randomized double-blind placebo-controlled study of sublingual HDM immunotherapy in 30 HDM-allergic subjects was performed, with 1-year open extension in 9 patients on active treatment. HDM-stimulated blood mononuclear cells were analyzed for proliferation, cytokines, and regulatory T cells (Tregs) by flow cytometry and ELISA. Effects of blocking transforming growth factor (TGF)-beta and IL-10 on proliferation were determined. Treg suppressor function and allergen-specific antibody levels were measured. Clinical efficacy was assessed by symptom, medication, and Juniper quality-of-life scores.

MEASUREMENTS AND MAIN RESULTS

Allergen-induced CD4(+) T-cell division and IL-5 production were significantly decreased after 6- and 12-months' active treatment but not placebo. sTGF-betaRII blocked immunotherapy-induced suppression of allergen-specific T-cell proliferation, maximal at 6 months. Decreased allergen-specific CD4(+) T-cell proliferation and increased IL-10 secretion and serum Der p 2-specific IgG(4) were maximal at 24 months' active treatment. Treg (CD4(+)CD25(+)CD127(lo)/Foxp3(+)) function was demonstrated by suppression of allergen-specific effector T-cell (CD4(+)CD25(-)CD127(hi)) proliferation and cytokine production. Clinical efficacy of immunotherapy was supported by significantly decreased rhinitis symptom score, total asthma score, and Juniper quality-of-life score.

CONCLUSIONS

This study establishes the novel finding that TGF-beta mediates the immunological suppression seen early in clinically effective sublingual HDM immunotherapy in addition to an increase in Tregs with suppressor function. Clinical trial registered with www.clinicaltrials.gov (NCT00250263).

Mechanisms of sublingual immunotherapy

Allergen-specific sublingual immunotherapy is now recognized to be an efficacious and well-tolerated treatment for allergic rhinitis. Emerging treatment strategies are also aimed at the primary treatment of allergic asthma, particularly allergy to house dust mites. Knowledge of the exact mechanisms of action of sublingual immunotherapy is at a basic level, although there appear to be similarities to the immunological changes seen in subcutaneous immunotherapy. An improved understanding should allow the development of more effective treatment programs and widen the potential use of this form of immunotherapy. This review discusses the possible mechanism of action of sublingual immunotherapy, including data from animal and clinical studies, while comparing this with the current understanding of subcutaneous immunotherapy.

Clinical and Immunological Correlates of Pre-Co-Seasonal Sublingual Immunotherapy with Birch Monomeric Allergoid in Patients with Allergic Rhinoconjunctivitis

Sublingual immunotherapy is safe and efficacious in the treatment of patients with allergic rhinitis. The clinical and biological efficacy of modified allergens (allergoids) has not been fully clarified. We investigated in birch allergic patients the effect of a pre-co-seasonal sublingual immunotherapy regimen with a modified allergen extract on clinical parameters and on T cell proliferation and regulatory cytokine production (IL-10, TGF-beta). We found that during the birch pollen season symptoms and drug usage scores were 30 and 40% improved, respectively, in treated versus control subjects (p<0.0001 for both comparisons) whereas well days were 23.5 (33%) versus 16.9 (23%) (p=0.0024), respectively. Bet v 1 allergen specific proliferation decreased (p = 0.0010), whereas IL-10 transcription increased (p = 0.0010) in treated, but not in control patients. Moreover, TGF-beta transcription was increased, although not significantly (p=0.066), following immunotherapy. Thus, sublingual immunotherapy with modified allergen in birch-allergic subjects was safe, clinically efficacious and associated with the reduction of allergen-specific proliferation and with the increased production of the IL-10 regulatory cytokine.

Subcutaneous and sublingual immunotherapy in children: complete update on controversies, dosing, and efficacy

For this review, articles on immunotherapy dosing in pediatric respiratory allergy were identified via PubMed, through congressional abstracts for 2008, in reference lists of recent review articles, and via personal communication with experts. In pediatric subcutaneous immunotherapy (SCIT), doses shown to be effective, mostly in aluminium-adsorbed preparations administered every 6 weeks, contain 20 microg of group 5 major allergen, 12 microg Bet v 1, 15 microg Fel d 1, and 5 to 20 microg Der p 1. Evidence indicates that SCIT prevents new sensitizations and asthma onset 7 years after discontinuation and reduces symptoms 12 years after a 5-year SCIT course, even though skin reactivity returns. Consistent evidence of effect exists for sublingual immunotherapy in pediatric respiratory allergy with daily 15- to 25-microg grass group 5 major allergen and 6 microg Bet v 1. Der p/f doses of 0.8/0.4 microg three times weekly (up to 27/57 microg daily) demonstrate inconsistent findings. Evidence of effect exists for SCIT in pediatric allergic rhinitis and asthma as treatment and preventive management. Evidence of effect exists for sublingual immunotherapy in pediatric allergic rhinoconjunctivitis and seasonal asthma. Similar results are doubtful for perennial asthma.

Early Cytokine Modulation after the Rapid Induction Phase of Sublingual Immunotherapy with Mite Monomeric Allergoids

The influence of different treatment schedules of sublingual immunotherapy (SLIT) in activating IL-10-producing T-cells, crucial in inducing allergen-specific tolerance, is not completely understood. The present work was designed to evaluate allergen driven interleukin release by mononuclear cells in the early phase of SLIT, after application of different induction schemes. Twenty mite-allergic patients were enrolled, 10 (group A) treated with a traditional 98 day induction scheme and 10 (group B) with a 16 day scheme with monomeric allergoid vaccine. At the end of the induction phase, the cumulative doses taken by group A and group B patients were equivalent to 50.5 and 50.3 μg of mite group 1 allergens, respectively. The release of Th1-, Th2- and Treg-related interleukins was assessed in culture supernatants of 5 μg/ml Der-p1-stimulated mononuclear cells, isolated before and after the induction phases. No relevant treatment-related side effects were observed. Interleukin release was similar in the two groups at the enrolment. Non-stimulated and Der p 1 stimulated release of studied cytokines was similar in the two groups at enrolment. Der p 1 stimulation significantly increased IL-10 release (p<0.0002) after treatment in group B patients, and this effect was higher (p=0.05) compared to group A patients. Furthermore, at the end of SLIT induction TNF-alpha, IL-4 and IFN-gamma production were reduced in group B patients (p<0.05, p=0.062 and p=0.060, respectively). The rapid induction scheme of sublingual immunotherapy induces an early immune suppression more effectively than the slower one. The rapid induction scheme should be the preferential way to start sublingual immunotherapy, particularly when monomeric allergoids are utilized.

Sublingual Desensitization in Patients with Wasp Venom Allergy: Preliminary Results

The aim of this paper is to assess in an open prospective pilot case-control study the tolerability, safety and efficacy of an ultra-rush sublingual immunotherapy (SLIT) protocol with Vespula venom in wasp allergic patients compared to subcutaneous immunotherapy (SCIT). Forty-one wasp allergic patients were treated with sublingual (SLIT group) or subcutaneous (SCIT group) ultrarush immunotherapy with Vespula venom extract. All patients underwent skin tests and serum specific IgE and IgG4 detection before enrolment and after 6, 12 and 24 months of immunotherapy. The SLIT group consisted of 21 (6 females and 15 males) patients who received increasing doses of Vespula venom (Aquagen, ALK-Abelló) until the final dose of 30 drops of extract in 3 hours, containing 100,000 SQ-U/ml. The maintenance dose was of 10 drops of pure venom extract 3 times a week, for a total dose of 100,000 SQ-U weekly (corresponding to 100 μg of venom extract). The SCIT group consisted of 20 patients (16 males and 4 females) who were treated with subcutaneous ultrarush immunotherapy with Vespula venom extract (Pharmalgen, Alk-Abelló). Patients received 101.1 μg of Vespula venom in 3 hours and were treated with 100 μg of wasp venom monthly. During the ultrarush sublingual treatment 2 patients (9.5%) experienced mild side-effects. Specific IgE and specific IgG to wasp venom did not show any significant modification. Four patients were field-stung by a wasp during the treatment (for a total of 6 stings). Two patients (3 stings), with a previous clinical history of a grade III and IV reaction, did not experience any reaction. One patient, with a previous grade II reaction, showed a large local reaction. The fourth patient, with a previous grade III reaction, was re-stung twice (after 12 and 24 months) with two systemic reactions (SR) (mild throat constriction). During the ultrarush SCIT phase, 3 (15%) patients experienced side-effects: 2 of them showed a large local reaction and 1 had headache and stomach ache. Specific IgE showed a significant (P=0.001) increase after 6 months of treatment and then returned to baseline levels while specific IgG showed a significant (P=0.001) increase after 6, 12 and 24 months in comparison with baseline. Nine patients were field-stung during the treatment: 8 of them experienced large local reactions; one patient (11%) experienced an SR (dizziness). Our results, even if in a small number of patients, suggest that in patients with Hymenoptera sting allergy SLIT could be efficacious with a good tolerability profile when compared to SCIT. Larger studies are needed to assess efficacy, safety and tolerability profile of wasp venom SLIT.

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.

Allergen-induced in vitro expression of IL-18, SLAM and GATA-3 mRNA in PBMC during sublingual immunotherapy

BACKGROUND

Signalling lymphocytic activation molecule (SLAM) and interleukin (IL)-18 induce interferon (IFN)-gamma production from Th1 cells. The allergen-induced SLAM and IL-18 mRNA expressions are increased during subcutaneous immunotherapy (SCIT), but nothing is known about their role during sublingual immunotherapy (SLIT). Transcription factor GATA-3 is associated with Th2 cells but its role in SCIT and SLIT is yet unexplored. This study was undertaken to analyse the allergen induced in vitro mRNA expression of IL-18, SLAM and GATA-3 in peripheral blood mononuclear cells (PBMC) of children with allergic rhinitis (AR) during SLIT.

METHODS

Ten patients with AR undergoing pollen SLIT with a weekly dose of 200,000 SQ-U, 10 with 24,000 SQ-U of mixture of Betula verrucosa, Corylus avellana and Alnus glutinosa and 10 with placebo were included. Peripheral blood mononuclear cell were stimulated with birch extract prior to, after 1 and 2 years of the treatment. The mRNA expression was assessed using kinetic real-time RT-PCR (TaqMan); Applied Biosystems, Foster City, CA, USA).

RESULTS

The expression of IL-18 mRNA was increased in the high-dose group in comparison to the placebo group after 1 year of therapy (P = 0.028) and had an inverse correlation with the late phase skin reaction after the second study year (r = -0.41, P = 0.041). SLAM mRNA expression increased in the high-dose group from baseline to 1 year (P = 0.028) and correlated with IL-10 (r = 0.96, P < 0.0001) and transforming growth factor-beta (r = 0.80, P = 0.0037) mRNA expression. No significant changes were seen in GATA-3 mRNA expression.

CONCLUSIONS

During SLIT, IL-18 and SLAM are upregulated, suggesting that the Th2 type inflammatory response is downregulated during SLIT by increased Th1 type response.

Allergic rhinitis and its impact on asthma update: allergen immunotherapy

The Allergic Rhinitis and its Impact on Asthma document was first published in 2001. Since then, new data on specific immunotherapy have appeared. This review is intended as an update to the original document. MedLine (2001 to June 2006) was searched with appropriate key words, and panelists were asked to identify further relevant articles. Randomized controlled trials were considered for the evaluation of efficacy. For the evaluation of safety and additional effects, studies with lower grades of evidence were included. The clinical efficacy of injection immunotherapy in rhinitis and asthma was confirmed, as well as the safety, provided that recommendations are followed. Studies have demonstrated the long-term efficacy and the preventive effect of immunotherapy in reducing the onset of new sensitizations. One randomized open trial demonstrated that in children with allergic rhinitis, injection immunotherapy may reduce the risk of developing asthma. There is strong evidence that sublingual immunotherapy is effective in allergic rhinitis in adults. Recent meta-analyses demonstrated its efficacy in allergic rhinitis in children and in asthma, although more definitive trials are required. Current data indicate that sublingual immunotherapy is safe and the rate of adverse reactions is not greater below 5 years of age. One randomized open trial showed that in children with allergic rhinitis, sublingual immunotherapy reduced the onset of asthma. Further studies are needed to identify the optimal maintenance dose and to elucidate the mechanism of action. Novel approaches for immunotherapy are currently under evaluation, including the use of adjuvants, peptides, and DNA-conjugated and recombinant allergens.

Sublingual immunotherapy: update 2006

PURPOSE OF REVIEW

Sublingual immunotherapy is currently accepted as a viable therapeutic option, and is widely used in many European countries. In the past 2 years, new data concerning clinical, immunological and practical aspects of sublingual immunotherapy have been published, and many critical points have been addressed.

RECENT FINDINGS

In addition to the new data on clinical efficacy, the most recent studies have shown that, similar to the injection route, sublingual immunotherapy can also prevent the onset of new sensitizations and the onset of asthma. Moreover, several postmarketing surveys have confirmed the satisfactory safety profile, even in very young children, and compliance has been measured. The good safety profile has also suggested the possibility of using sublingual immunotherapy without the updosing phase. Finally, the mechanisms of action have been systematically investigated and the biodistribution of sublingual allergens has been further clarified.

SUMMARY

More new data on sublingual immunotherapy are rapidly appearing in the international literature. These data consistently confirm the value of this treatment and show that sublingual immunotherapy is a viable and useful form of immunotherapy.

Evaluation of serum IgG4 antibodies specific to grass pollen allergen components in the follow up of allergic patients undergoing subcutaneous and sublingual immunotherapy

BACKGROUND

A number of reports suggest that induction of IgG 'blocking antibodies' may be important for successful allergen immunotherapy. Nevertheless, a significant increase in specific IgG and IgG4 antibodies has not been consistently demonstrated for sublingual immunotherapy (SLIT).

METHODS

The present observation included three groups of grass pollen allergic patients all submitted to three different allergen immunotherapeutic regimens in an open, non-placebo controlled clinical study: (i) 16 patients underwent a modified 'cluster' regimen of weekly injections of a standardized aluminium-absorbed Phleum pratense extract for 5 weeks, followed by 3 weeks of maintenance injections. (ii) Fifteen patients were treated with standardized timothy grass pollen-allergen oral vaccine. In the first session of a SLIT protocol without up-dosing, each patient received 2.4 ml of sublingual vaccine containing about 57 microg of Phl p 5 and received a maintenance dose of 24 microg of Phl p 5 once a day for 120 days. (iii) Fourteen subjects were treated with a standardized allergen extract containing 5-grass pollen mixture; a SLIT protocol was performed without up-dosing, administering a dose corresponding to about 10.0 microg/ml grass-pollen Group 5 and a maintenance dose of 4 microg of grass-pollen Group 5 once a day for 135 days. Patients' sera were characterized in detail by determining IgG4 antibodies to rPhl p 1, 2, 5, 6, 7, 11, 12 and nPhl p 4 and eosinophil cationic protein before the start of immunotherapy and during the peak of pollen season.

RESULTS

No relevant systemic side effects were registered in patients treated with the modified cluster subcutaneous immunotherapy (SCIT) protocol and the two SLIT protocols without build-up phase. After SCIT all patients had high titres of serum allergen-specific IgG4 antibodies. High-dose SLIT led to an IgG4 increase comprising 25% of the SCIT level, while low-dose SLIT increased to 4% of the SCIT. Furthermore, the increase of specific IgG antibodies corresponds to a decrease of serum ECP during allergen exposure.

CONCLUSIONS

These preliminary data seem to indicate that: (i) pre-seasonal high-dose SLIT protocol without build-up phase is safe and well-tolerated by allergic patients; (ii) compared to IgG4 levels induced by SCIT, only a high-dose SLIT regimen results in an appreciable serum specific IgG4 increase.

Sublingual immunotherapy in children modulates allergen-induced in vitro expression of cytokine mRNA in PBMC

BACKGROUND

During subcutaneous immunotherapy (SCIT), there is a local mucosal shift from Th2 to Th1 type cytokine predominance and downregulation of interleukin (IL)-5 and eosinophilia. According to recent studies IL-10- and transforming growth factor (TGF)-beta-induced tolerance is another key phenomenon in SCIT. Few data to date is available on mechanisms and roles of these cytokines in sublingual immunotherapy (SLIT).

SCOPE

This study was undertaken to analyse the allergen-induced in vitro mRNA expression of IL-4, IL-5, IL-10, TGF-beta and interferon (IFN)-gamma during SLIT in peripheral blood mononuclear cells (PBMC) of children with allergic rhinitis (AR).

METHODS

Ten patients with AR undergoing pollen SLIT with a weekly dose of 200,000 SQ-U, 10 with a weekly dose of 24,000 SQ-U of glycerinated mixture of Betula verrucosa, Corylus avellana and Alnus glutinosa and 10 with placebo were included in the study. Peripheral blood mononuclear cell samples were collected and stimulated with pollen allergen extract prior to the treatment, after 1 and 2 years of the treatment. The cytokine mRNA expression was assessed using kinetic real time reverse transcription polymerase chain reaction (RT-PCR; TaqMan).

RESULTS

The in vitro allergen-induced mRNA expression of IL-5 by PBMC in the placebo group at 1 (P = 0.0065) and 2 (P = 0.013) years of therapy were increased in comparison with the highest dose. The expression of IL-10 mRNA was increased in the highest dose group (P = 0.0016) and the lower dose group (P = 0.034) at 2 years of therapy when compared with placebo. The change in the expression of allergen-induced TGF-beta had an inversed correlation with the change of IL-5 (r = -0.38, P = 0.036) and positive correlation with the change of IL-10 (r = 0.58, P = 0.0019).

CONCLUSIONS

Sublingual immunotherapy induced a dose-dependent systemic allergen-specific immunological response in children with AR. During high-dose SLIT, there was activation of regulatory cytokine IL-10 and an inhibitory effect on IL-5 expression increase that was associated with TGF-beta.

Sublingual immunotherapy induces spirometric improvement associated with IL-10 production: Preliminary reports

BACKGROUND

Sublingual immunotherapy (SLIT) has been demonstrated to be able of inducing immunologic changes as evidenced by IL-10 production. Forced expiratory flow between 25% and 75% of the vital capacity (FEF(25-75)) may be considered a good marker of early bronchial involvement in patients with pure allergic rhinitis.

OBJECTIVE

The aim of this study was to evaluate the possible association of IL-10 production with FEF(25-75) values in patients with perennial allergic rhinitis (PAR) successfully treated with SLIT.

METHODS

19 patients with PAR were studied: 9 successfully assumed SLIT for 3 years, 10 were considered as control. In vitro IL-10 production was evaluated after SLIT. Spirometry and bronchodilation test were performed in all subjects at baseline and after 3 years.

RESULTS

After 3 years, FEF(25-75) values significantly (p=0.0131) increased in SLIT group (80.5+/-6.7), whereas they significantly (p=0.0021) decreased in non-treated patients (60.8+/-2.62). In addition, SLIT-induced increase of FEF(25-75) values is significantly associated with IL-10 production (p=0.0025).

CONCLUSIONS

This study provides the first evidence that SLIT is capable of improving early bronchial involvement in patients with pure allergic rhinitis and this functional effect may be associated with immunological changes, such as the induction of IL-10 production.