Immunomodulation during sublingual therapy in allergic children

Efficacy of sublingual immunotherapy in asthma: systematic review of randomized-clinical trials using the Cochrane Collaboration method

BACKGROUND

Sublingual immunotherapy (SLIT) is effective and safe in the treatment of allergic rhinitis. However, there is no meta-analysis in asthma treatment.

METHODS

The clinical efficacy of SLIT for asthma was evaluated through a systematic review with meta-analysis. MEDLINE (1966-2005), EMBASE (1974-2005), LILACS (1982-2005), and the Cochrane Library were searched for related literature in any language. Randomized-controlled clinical trials (RCT) on SLIT in asthma treatment for adults and children were selected. From 119 citations, 25 studies with 1706 patients were included in this meta-analysis. For each report, quality scores were assigned and data were extracted in relation to the outcomes analyzed: asthmatic symptoms, use of asthma medications, lung function, and bronchial provocation.

RESULTS

According to the Jadad quality method, 64% of the studies were assigned scores of 4 or 5. Immunotherapy was seen to significantly reduce asthma severity when parameter compositions were all analyzed by categorical outcomes. There was a nonsignificant reduction in asthma symptoms when analyzed using standardized mean differences. No severe reactions were observed.

CONCLUSIONS

This meta-analysis found that SLIT is beneficial for asthma treatment albeit the magnitude of the effect is not very large. Moreover, it is a safe alternative to the subcutaneous route. More RCT with standardization of symptom scores and medications are needed in order to contribute further to this subject.

Sublingual immunotherapy of allergic diseases

The only disease-modifying treatment that is available for allergic patients is allergen-specific immunotherapy. Two competing application forms are used: subcutaneous immunotherapy, which has been used for > 90 years, and a relatively new immunotherapy where the allergen is applied sublingually. Numerous studies have shown efficacy for subcutaneous immunotherapy and have identified possible mechanisms that are responsible for the observed reduction in allergic responses. In contrast, the efficacy of sublingual immunotherapy has not been documented to the same degree and the responsible immunological mechanisms have not yet been clearly defined. This review focuses on the published clinical and experimental data on sublingual immunotherapy and points at possible mechanisms of how sublingual immunotherapy may differ from subcutaneous immunotherapy in its mode of action, and also discusses the potential advantages and pit falls of both therapies.

Efficacy of sublingual immunotherapy in the treatment of allergic rhinitis in pediatric patients 3 to 18 years of age: a meta-analysis of randomized, placebo-controlled, double-blind trials

OBJECTIVE

To evaluate the efficacy of sublingual immunotherapy (SLIT) in the treatment of allergic rhinitis in children.

DATA SOURCES

A comprehensive search of the EMBASE, MEDLINE, LILACS, and CINAHL databases from January 1966 to February 10, 2006, was performed.

STUDY SELECTION

Randomized, double-blind, placebo-controlled trials of SLIT in the treatment of allergic rhinitis in patients 18 years or younger were selected. Outcomes measured were symptom scores and rescue medication use. Analysis was performed with standardized mean differences (SMDs) and a random-effects model.

RESULTS

Seventy articles were identified and reviewed. Ten studies, published between 1990 and 2004, fulfilled the selection criteria. Five hundred seventy-seven patients were initially included in the studies. Of these patients, 484 (245 SLIT and 239 placebo) had a final clinical evaluation and could be evaluated. A relevant heterogeneity due to widely differing scoring systems was found. Overall, there was a significant reduction in both symptoms (SMD, 0.56, 95% confidence interval, 1.01-0.10; P = .02) and medication use (SMD, 0.76; 95% confidence interval, 1.46-0.06; P = .03) after immunotherapy. The subanalyses performed for treatment duration and type of allergen showed that SLIT for more than 18 months and with pollen extracts was effective compared with SLIT courses shorter than 18 months and with mites.

CONCLUSION

The results of this meta-analysis showed that,compared with placebo, SLIT with standardized extracts is effective in pediatric patients with allergic rhinitis.

Novel ways for immune intervention in immunotherapy: mucosal allergy vaccines

Allergen-specific immunotherapy is currently the only curative treatment for allergy. Subcutaneous immunotherapy (SCIT) has been successfully used to treat patients who are allergic to insect venom, house dust mites, or tree or grass pollens. In the context of potentially severe, albeit infrequent, side effects associated with SCIT, mucosal routes of administration are being investigated to conduct allergenic desensitization. This article reviews recent developments in the field of nasal, oral, and sublingual immunotherapy as they relate to safety, clinical efficacy, and immune mechanisms of action. Implications for the design and development of improved allergy vaccines that could be used through such nonparenteral routes are discussed. Specifically, allergen presentation platforms and adjuvants facilitating the targeting of immune cells at mucosal surfaces to promote tolerance induction are reviewed.

Psychological stress affects response to sublingual immunotherapy in asthmatic children allergic to house dust mite

While the clinical and immunologic efficacy of sublingual immunotherapy (SLIT) in allergic diseases has been extensively demonstrated, some patients display a poor clinical response. Psychological stress has been shown to play a role in atopy and also to affect response to immunomodulating therapies such as vaccination with microbial antigens. This study addresses the possibility of response to SLIT being affected by psychological stress. Forty children with mild asthma caused by allergy to Dermatophagoides pteronyssinus and farinae were subjected to SLIT and then divided after 6 months into two groups based on the results of the stress integrated measure (SIM) test: group 1 (24 stressed patients, mean SIM value of 60.1) and group 2 (16 non-stressed patients, mean SIM value of 7.6). There was also a higher prevalence of psychosocial stressing factors (divorced/absent parents, low income households, non-working parents) among stressed patients. The symptom score, peak expiratory flow (PEF), forced expiratory volume in 1 s (FEV(1)) and serum eosinophie cationic protein (ECP) concentration were evaluated at both times. The serum concentration of neuroendocrine parameters [prolactin, cortisol, adrenocorticotropic hormone (ACTH)] was also measured after 6 months of therapy. While all the clinical parameters and ECP concentration improved after SLIT, symptom score, PEF and ECP showed a significantly greater improvement in non-stressed patients. The concentration of neuroendocrine parameters was significantly increased in stressed patients. Our findings show that psychological stress can affect response to SLIT also in allergic subjects and are consistent with data recently reported showing a correlation between stress and poor response to antimicrobial vaccines. Our data also suggest that stress evaluation may become a useful prognostic factor in immunotherapy.

Randomized double-blind controlled study with sublingual carbamylated allergoid immunotherapy in mild rhinitis due to mites

BACKGROUND

The clinical efficacy of sublingual immunotherapy (SLIT) in mite allergy and in mild disease is still a matter of debate, thus we performed a long-term clinical trial.

METHODS

The study was randomized, double-blind and placebo-controlled. After a 1-year assessment, 68 patients with mild rhinitis with/without asthma due to mites were randomized to drugs + placebo or drugs + SLIT for 2 years. Sublingual immunotherapy was given as soluble tablets of monomeric carbamylated allergoid. Clinical scores for asthma and rhinitis (0, absent to 3, severe) and drug consumption were assessed by diary card in the period November-February. Quality of life was assessed before and after each observation period and pharmaco-economy data were evaluated as well.

RESULTS

Fifty-six patients completed the study. The rate of dropouts was similar in the two groups. No relevant side effect was reported. There was a significant reduction of total clinical scores (P < 0.05) in the active group vs placebo at the first year, but not at the second whereas nasal obstruction significantly improved in both years (P < 0.05). The reduction of drug intake score was significant only at the first year. No change was observed concerning most of the Short Form-36 items, because at baseline all patients displayed a normal profile. A significant change in SLIT group was seen for the item 'change in health status'. The need for extra visits was significantly lower in the active group (25%vs 43%).

CONCLUSIONS

Sublingual immunotherapy was clinically effective and safe in mite-induced mild disease.

Sublingual immunotherapy: a comprehensive review

Sublingual immunotherapy (SLIT) has been used with increasing frequency in Europe and is viewed with increasing interest by allergists in the United States. To address this interest, a Joint Task Force of the American College of Allergy, Asthma and Immunology and the American Academy of Allergy, Asthma and Immunology's Immunotherapy and Allergy Diagnostic Committees reviewed the available literature on SLIT and prepared this report. The task force concluded that despite clear evidence that SLIT is an effective treatment, many questions remained unanswered, including effective dose, treatment schedules, and overall duration of treatment. Until these have been determined, an assessment of the cost/benefit ratio of the treatment cannot be made. SLIT does appear to be associated with few serious side effects, but it has not been administered in high-risk asthmatic patients, nor in the studies reviewed has it been administered as a mixture of non-cross-reacting allergens. Furthermore, there is currently no allergy extract approved for this use in the United States, nor is there a Current Procedural Terminology code for billing purposes. All of these factors should be given careful consideration by anyone contemplating initiating SLIT treatment for their allergic patients.

Advances in allergen-specific immunotherapy

Atopic disease affects approximately 30% of the population in western society. Allergen-specific immunotherapy (SIT) is the only treatment with a long-term effect available at the present time, and has been used successfully in the treatment of a number of allergies for almost 100 years. Despite this success, there is great demand for safer, faster and more effective approaches. At present, many studies are being conducted aiming to comply with this demand. The approaches used include conventional immunotherapy, using allergen extracts, as well as novel methods such as peptide immunotherapy, allergen DNA vaccines and non-injection routes of SIT. The clinical success of various treatments, new technical developments and a better understanding of the immunological mechanisms behind immunotherapy hold great potential for the broad application of allergen-SIT in the foreseeable future.

Update on sublingual immunotherapy

OBJECTIVE

To obtain a current understanding of the mechanisms, clinical indications, efficacy, and safety of sublingual immunotherapy (SLIT) for the treatment of children and adults with allergic rhinitis, asthma, and allergic conjunctivitis.

METHODS

A MEDLINE and Index Medicus search for peer-reviewed articles on SLIT was performed.

RESULTS

Since the approval of SLIT by the World Health Organization in 1988, the efficacy and safety of SLIT have been confirmed in several new double-blind, placebo-controlled studies for monosensitized patients who are allergic to house dust mites, grass pollens, ragweed, and birch pollen. Documented immunologic responses to SLIT have included a decrease in serum eosinophilic cationic protein and interleukin 13 (IL-13) levels, an elevation in IL-12 levels, a reduction in late-phase responses, and increases in IgG4/IgE ratios. A Cochrane review of 22 studies confirmed the efficacy and safety of SLIT for patients with allergic rhinitis. A long-term asthma study showed sustained efficacy 5 years after discontinuing the vaccine. The safety of SLIT has been confirmed in postmarketing studies, and severe systemic adverse effects have never been reported. In view of its safety profile, SLIT is taken by the patient at home (away from specialized centers), and no specialized resuscitation facilities are required.

CONCLUSION

SLIT is a safe and effective therapeutic option for patients with allergic rhinitis and asthma. Because of its efficacy, safety, and ease of administration, it has been accepted in Europe, Southern Africa, Australasia, Southeast Asia, and the Middle East as a promising therapeutic option that can significantly alter the natural history of allergic disease without the risks of injection immunotherapy.

IgG-blocking antibodies inhibit IgE-mediated anaphylaxis in vivo through both antigen interception and Fc gamma RIIb cross-linking

Although it has long been hypothesized that allergen immunotherapy inhibits allergy, in part, by inducing production of IgG Abs that intercept allergens before they can cross-link mast cell Fc epsilonRI-associated IgE, this blocking Ab hypothesis has never been tested in vivo. In addition, evidence that IgG-allergen interactions can induce anaphylaxis by activating macrophages through Fc gammaRIII suggested that IgG Ab might not be able to inhibit IgE-mediated anaphylaxis without inducing anaphylaxis through this alternative pathway. We have studied active and passive immunization models in mice to approach these issues and to determine whether any inhibition of anaphylaxis observed was a direct effect of allergen neutralization by IgG Ab or an indirect effect of cross-linking of Fc epsilonRI to the inhibitory IgG receptor Fc gammaRIIb. We demonstrate that IgG Ab produced during the course of an immune response or administered passively can completely suppress IgE-mediated anaphylaxis; that these IgG blocking Abs inhibit IgE-mediated anaphylaxis without inducing Fc gammaRIII-mediated anaphylaxis only when IgG Ab concentration is high and challenge allergen dose is low; that allergen epitope density correlates inversely with the allergen dose required to induce both IgE- and Fc gammaRIII-mediated anaphylaxis; and that both allergen interception and Fc gammaRIIb-dependent inhibition contribute to in vivo blocking Ab activity.

Immune mechanisms of allergen-specific sublingual immunotherapy

Sublingual immunotherapy has been shown in some clinical studies to modulate allergen-specific antibody responses [with a decrease in the immunoglobulin E/immunoglobulin G4 (IgE/IgG4) ratio] and to reduce the recruitment and activation of proinflammatory cells in target mucosa. Whereas a central paradigm for successful immunotherapy has been to reorient the pattern of allergen-specific T-cell responses in atopic patients from a T helper (Th)2 to Th1 profile, there is currently a growing interest in eliciting regulatory T cells, capable of downregulating both Th1 and Th2 responses through the production of interleukin (IL)-10 and/or transforming growth factor (TGF)-beta. We discuss herein immune mechanisms involved during allergen-specific sublingual immunotherapy (SLIT), in comparison with subcutaneous immunotherapy. During SLIT, the allergen is captured within the oral mucosa by Langerhans-like dendritic cells expressing high-affinity IgE receptors, producing IL-10 and TGF-beta, and upregulating indoleamine dioxygenase (IDO), suggesting that such cells are prone to induce tolerance. The oral mucosa contains limited number of proinflammatory cells, such as mast cells, thereby explaining the well-established safety profile of SLIT. In this context, second-generation vaccines based on recombinant allergens in a native conformation formulated with adjuvants are designed to target Langerhans-like cells in the sublingual mucosa, with the aim to induce allergen-specific regulatory T cells. Importantly, such recombinant vaccines should facilitate the identification of biological markers of SLIT efficacy in humans.

Efficacy of sublingual immunotherapy with high-dose mite extracts in asthma: a multi-center, double-blind, randomized, and placebo-controlled study in Taiwan

Sublingual immunotherapy (SLIT) has been recommended as a viable alternative to subcutaneous injection therapy in the treatment of airway allergies, though more data is needed from well-controlled studies for documenting its efficacy in different ethnic populations. Ninety-seven children (age range 6-12 years), mild-to-moderate asthma with a single sensitization to mite allergen, were enrolled from 5 medical centers in Taiwan to evaluate the efficacy and safety of SLIT with standardized mite extracts, which contain Dermatophagoides pteronyssinus (D.p.) and Dermatophagoides farinae (D.f.). Patients were double blinded and randomly assigned to either a SLIT or placebo group. Following 24 weeks of study period, symptom and medication scores, lung function tests, skin prick tests, total serum IgE, and specific IgE to D.p. and D.f. were recorded. The results showed that there was statistically significant difference between these two groups in the analysis of daily (P=0.011), nighttime (P=0.028), and daytime (P=0.009) asthmatic scores after 24 weeks of treatment. Patients receiving SLIT improved their forced vital capacity (FVC), forced expiratory volume in 1s (FEV1), and peak expiratory flow (PEF) as compared to baseline (P=0.042, P=0.048, and P=0.001, respectively). No differences were found in skin prick test, total serum IgE and specific IgE to D.p. and D.f. Tolerance with high-dose SLIT was good with few minor adverse events reported. Our results indicated that a 24-week SLIT is of clinical benefit to mite-sensitive asthmatic children in Taiwan.

Emerging anti-inflammatory agents for allergic rhinitis

Allergic rhinitis (AR) is a high-prevalence disease, affecting 10-15% of the general population. AR is sustained by an IgE-mediated reaction, and by a complex inflammatory network of cells, mediators and cytokines that becomes chronic when exposure to allergen persists. A T helper 2 (TH2)-biased immune response is the basis for the allergic inflammation. The current therapeutic strategy is mainly based on drugs (antihistamines, nasal corticosteroids, cromones, decongestants) and allergen immunotherapy. Drugs are overall effective in controlling symptoms, but do not modify the immune background that leads to allergic inflammation, and safety concerns may be present especially for prolonged treatments. Immunotherapy can modify the allergic response, but there is still space for improvement. Nowadays, several approaches are under investigation to optimise the management of AR. On one hand, new drugs and antimediators are being developed; on the other hand, attempts are made to selectively block relevant signal pathways of allergic reaction. Finally, one of the major goals is to modify the TH2-biased immune response by improving the characteristics and modes of action of allergen immunotherapy.

Pharmacokinetics of Der p 2 Allergen and Derived Monomeric Allergoid in Allergic Volunteers

BACKGROUND

Presently, sublingual immunotherapy is widely used as an alternative to the injection route for respiratory allergy, but its pharmacokinetics in humans is poorly known, and data are available only for Par j 1 allergen. We aimed at assessing the biodistribution of iodine-123-radiolabelled Der p 2 in allergic volunteers.

METHODS

Purified Der p 2 and its monomeric allergoid were radiolabelled with iodine-123 and administered sublingually to 7 allergic volunteers. The subjects were allowed to swallow 6 min after administration. Dynamic (up to 10 min) and static scintigraphic images (30 min, 1, 2, 3 and 20 h) were recorded, and blood samples were obtained at different time points to measure the plasma radioactivity and to assess the presence of circulating radiolabelled species by gel chromatography.

RESULTS

The local pharmacokinetics did not differ between allergen and allergoid. Plasma radioactivity began to increase only after swallowing and peaked at 1-2 h. Both the allergen and the allergoid persisted in the mouth for several hours, and traces could be detectable up to 20 h. At radioactivity plasma peak, gel chromatography showed that a fraction of the allergoid, but not the allergen, was absorbed as an intact molecule.

CONCLUSIONS

These results indicate that the pharmacokinetics of sublingual administration is independent of the allergen used and characterized by the long persistence in the mouth. The contribution of enteric absorption of the allergoid in the mechanism of action of sublingual immunotherapy remains to be defined.

Safety of sublingual-swallow immunotherapy in children aged 3 to 7 years

BACKGROUND

The minimum age to start specific immunotherapy with inhalant allergens in children has not been clearly established, and position papers discourage its use in children younger than 5 years.

OBJECTIVE

To assess the safety of high-dose sublingual-swallow immunotherapy (SLIT) in a group of children younger than 5 years.

METHODS

Sixty-five children (51 boys and 14 girls; age range, 38-80 months; mean +/- SD age, 60 +/- 10 years; median age, 60 months) were included in this observational study. They were treated with SLIT with a build-up phase of 11 days, culminating in a top dose of 300 IR (index of reactivity) and a maintenance phase of 300 IR 3 times a week. The allergens used were house dust mites in 42 patients, grass pollen in 11 patients, olive pollen in 5 patients, Parietaria pollen in 4 patients, and cypress pollen in 3 patients. All adverse reactions and changes in the treatment schedule were compared in 2 subgroups: children 38 to 60 months old and children 61. to 80 months old.

RESULTS

The average cumulative dose of SLIT was 36,900 IR. Adverse reactions were observed in 11 children, none of them severe enough to require discontinuation of immunotherapy. Six reactions occurred in the 60 months or younger age group and 7 in the older than 60 months age group, with no differences between these 2 groups.

CONCLUSION

High-dose immunotherapy in children younger than 5 years does not cause more adverse reactions than in children aged 5 to 7 years. There is no reason to forbear studies on safety and efficacy of these preparations in young children.

Post-marketing survey on the safety of sublingual immunotherapy in children below the age of 5 years

BACKGROUND

The age below 5 years is considered a prudential limit for immunotherapy in view of the possible severity of side-effects. Sublingual immunotherapy (SLIT) seems to be safe, but no study in very young children is available. We performed a safety post-marketing surveillance study in children below 5 years.

METHODS

Children aged 3-5 years with respiratory allergy receiving SLIT were followed-up for at least 2 years. A diary card for side-effects was filled by parents at each dose given. Local and systemic side-effects were graded as: mild (no intervention, no dose adjustment), moderate (medical treatment and/or dose reduction), severe (life-threatening/hospitalization/emergency care). The comparative safety of different allergens and regimens was also assessed.

RESULTS

One hundred and twenty-six children (mean age 4.2 years, 67 male) were included. Seventy-six (60%) had rhinitis with asthma, 34 (27%) rhinitis only and 16 (13%) only asthma. Immunotherapy was prescribed for mites (62%), grasses (22.2%), Parietaria (11.9%), Alternaria (2.4%) and olive (1.5%). Eighteen children underwent an accelerated build-up. The total number of doses was about 39,000. Nine side-effects were reported in seven children (5.6% patients and 0.2/1000 doses). Two episodes of oral itching and one of abdominal pain were mild. Six gastrointestinal side-effects were controlled by reducing the dose. All side-effects occurred during up-dosing phase. No difference in terms of safety among the allergens used was observed.

CONCLUSION

SLIT is safe also in children under the age of 5 years.

Sublingual immunotherapy in pediatric patients: beyond clinical efficacy

PURPOSE OF REVIEW

Sublingual immunotherapy (SLIT) is widely used in several European countries. Many clinical trials and a meta-analysis presently support its efficacy, but limits and indications in pediatric age still need to be clarified. We review here the most recent literature on SLIT, with particular attention paid to the safety of children and to the additional clinical effects.

RECENT FINDINGS

In addition to clinical trials, post-marketing surveillance studies have confirmed the optimal safety profile of SLIT in adults and children, including those below the age of 5 years. The most recent studies have shown that SLIT, identically to the subcutaneous route, has the potential to affect the immunological response to allergens. This is testified to by the facts that SLIT can prevent the onset of new sensitizations and maintain its beneficial effect for years after discontinuation. Moreover, it has been shown that SLIT can prevent the onset of asthma in children with rhinitis.

SUMMARY

Due to its excellent safety, SLIT would be an optimal candidate for use in pediatric age groups, where the natural history of allergy can be to some extent modified. Nonetheless, formal and rigorous studies are needed to define its exact indication and dosage.

Induction of interleukin 10 by sublingual immunotherapy for house dust mites: a preliminary report

BACKGROUND

Subcutaneous specific immunotherapy has been demonstrated to be capable of inducing T-cell regulatory response. Interleukin 10 (IL-10) plays a crucial role in inducing allergen-specific tolerance; however, no previous studies have examined IL-10 production after sublingual immunotherapy (SLIT).

OBJECTIVE

To evaluate T-cell proliferation and IL-10 production in patients successfully treated with SLIT for house dust mites (HDMs).

METHODS

Peripheral blood mononuclear cells were isolated from patients after at least 3 years of successful HDM SLIT and from matched untreated allergic patients and healthy control subjects. After 3 and 6 days of in vitro stimulation with phytohemagglutinin (PHA), Candida albicans, and Dermatophagoides farinae, proliferation and production of IL-10 were measured.

RESULTS

Patients treated with SLIT showed a significant reduction of proliferation induced by C albicans compared with untreated atopic patients (P < .001), but a significant reduction was also demonstrated in healthy controls compared with untreated atopic patients (P < .001). Patients treated with SLIT also showed a significant increase of IL-10 production after Candida and PHA stimuli compared with patients with untreated rhinitis (P < .001 for both). Patients with untreated rhinitis did not produce IL-10.

CONCLUSION

This preliminary study confirms reduced T-cell proliferation and preliminarily provides the first evidence, to our knowledge, of peripheral IL-10 production in allergic patients successfully treated with HDM SLIT.

The safety of sublingual-swallow immunotherapy: an analysis of published studies

BACKGROUND

As the main target of sublingual immunotherapy (SLIT) is to reduce at most the occurrence of adverse events (AE), safety represents a critical issue. This aspect deserves particular mention when a higher dose of allergen extract than traditional subcutaneous immunotherapy (SCIT) is required to be effective: that may be up to 500 times that employed for SCIT.

OBJECTIVE

All published controlled studies concerning SLIT-swallow were analysed to evaluate AE rates.

METHODS

Studies were subdivided in two groups: (i) studies using low allergen dose (LAD), i.e. ranging from 1 to 50 times the dose commonly administered with SCIT, and (ii) studies with high allergen dose (HAD), i.e. ranging from 50 to 500 times the dose administered with SCIT.

RESULTS

Twenty-five studies were altogether analysed: 13 studies belonged to the low-dose group, 12 belonged to the high-dose group. We considered all patients with at least one AE. Local reactions were significantly more frequent in the LAD group than in the HAD group (P<0.0001), while there was no difference in the rate of systemic reactions. Severe systemic reactions were never reported.

CONCLUSION

This study represents the first analysis of the safety of SLIT concerning the allergen dose employed in the treatment. There is evidence that AE occurrence is substantially not dose-dependent. This fact highlights two main clinical aspects: the elevated tolerability of SLIT in general and the safety of HAD regimen.

Lack of detectable alterations in immune responses during sublingual immunotherapy in children with seasonal allergic rhinoconjunctivitis to grass pollen

BACKGROUND

Recent work indicates that subcutaneous specific immunotherapy induces specific T-cell anergy, a shift in the TH1/TH2 ratio, and antibody production in favor of IgG4. There are few data on sublingual immunotherapy (SLIT), especially in children.

METHODS

We assessed the proliferation of peripheral blood mononuclear cells ((3)H-thymidine incorporation) and secretion of interleukin (IL)-4, interferon (IFN)gamma and IL-5 (ELISA) after in vitro stimulation with allergen or phytohemagglutinin (PHA) in 29 children with allergic rhinoconjunctivitis receiving SLIT with grass pollen before, and after 1 and 2 years of treatment in a multicenter placebo-controlled study on the efficacy of the treatment. Further, non-specific intracellular production of IL-4, IL-13, IFNgamma, IL-2, IL-10 and IL-5 (FACS) and serum total and specific IgE and IgG4 (ELISA) were analyzed.

RESULTS

Proliferation and IL-4 and IL-5 secretion after stimulation with allergen or PHA did not differ between the groups. In addition, we observed no effect of SLIT on intracellular cytokine production. IFNgamma secretion after allergen coculture was comparable between the groups. Following PHA stimulation, IFNgamma secretion was significantly higher in the SLIT group after 1 year, and a trend was observable already before and after 2 years of treatment, probably due to the inhomogeneity in the groups despite randomization (for age and asthma). No significant changes were observed for sIgE/sIgG4 ratios over time either in or between the groups.

CONCLUSION

During 2 years of SLIT in children with a positive effect on rescue medication use, we observed no significant effects on in vitro T-cell immune responses or immunoglobulins. So far, pediatric studies demonstrating stable effects of SLIT on such reactions are missing, probably due to limited effects of SLIT on systemic immunologic reactions.

Prolactin and autoimmunity

The interrelationship between prolactin (PRL) and the immune system have been elucitaded in the last decade, opening new important horizons in the field of the immunoendocrinology. PRL is secreted not only by anterior pituitary gland but also by many extrapituitary sites including the immune cells. The endocrine/paracrine PRL has been shown to stimulate the immune cells by binding to PRL receptors. Increased PRL levels, frequently described in autoimmune diseases, could depend on the enhancement of coordinated bi-directional communications between PRL and the immune system observed in these diseases. Hyperprolactinemia has been described in the active phase of some non organ-specific autoimmune diseases, as systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) and organ-specific autoimmune diseases, as celiac disease, type 1 diabetes mellitus, Addison's disease, autoimmune thyroid diseases. In these diseases PRL increases the syntesis of IFNgamma and IL-2 by Th1 lymphocytes. Moreover, PRL activates Th2 lymphocytes with autoantibody production. Of particular interest is the association between hyperprolactinemia and levels of anti DNA antibodies, islet cell antibodies (ICA), thyreoglobulin antibodies (TgAb), thyroperoxidase antibodies (TPOAb), adrenocortical antibodies (ACA), transglutaminase antibodies (tTGAb) in SLE, in type 1 diabetes mellitus, in Hashimoto's thyroiditis, in Addison's disease and in celiac disease, respectively. High levels of PRL have been also frequently detected in patients with lymphocytic hypophysitis (LYH). Several mechanisms have been invoked to explain the hyperprolactinemia in LYH. The PRL increase could be secondary to the inflammatory process of the pituitary gland but, on the other hand, this increase could have a role in enhancing the activity of the immune process in LYH. Moreover, the detection of antipituitary antibodies targeting PRL-secreting cells in some patients with idiopathic hyperprolactinemia suggests the occurrence of a possible silent LYH in these patients. Finally, the role of anti-prolactinemic drugs to inactivate the immune process in LYH is still discussed.

Sublingual and oral immunotherapy

Sublingual immunotherapy (SLIT) is a viable alternative to the subcutaneous route for the treatment of respiratory allergy, whereas the pure oral route has been abandoned because of its lack of efficacy. The main distinctive feature of SLIT is its optimal safety profile, which has been demonstrated in adults and children. The indications for SLIT are similar to those for the subcutaneous route. A long-lasting effect has been demonstrated for the sublingual route, but data are needed to determine the optimal dose and the preventive effect in asthma.

Sublingual immunotherapy: an update

PURPOSE OF REVIEW

Sublingual immunotherapy is now officially accepted as a viable alternative to the traditional subcutaneous route, and it is widely used especially in European countries. Despite the large amount of experimental evidence on the safety and efficacy of the method, some concerns still exist, and several aspects need to be clarified: magnitude of the efficacy, adherence, long-lasting effect and others. Recently published studies have provided answers to some of these points.

RECENT FINDINGS

The most recent studies have shown that sublingual immunotherapy exerts a long-lasting effect up to 5 years after discontinuation and that it is able to prevent the onset of new sensitizations. Moreover, when systematically assessed, the adherence to treatment is quite satisfactory, despite the treatment being self-administered. In addition, evidence has been provided that sublingual immunotherapy is effective in treating allergic conjunctivitis, and a metaanalysis has confirmed its efficacy in rhinitis. Moreover, some studies have addressed the possibility of simplifying the schedule of administration by shortening the build-up phase.

SUMMARY

More and more new data on sublingual immunotherapy are rapidly appearing in the international literature. These data confirm the clinical value of this treatment and show that it is comparable to subcutaneous immunotherapy from several points of view.

Efficacy and safety of sublingual immunotherapy

OBJECTIVE

To review the available published data concerning the use of sublingual immunotherapy (SLIT) in respiratory allergy to primarily evaluate the clinical efficacy and safety of the treatment and to secondarily consider the mechanisms of action and any unresolved questions.

DATA SOURCES

Articles in the medical literature (starting from 1986 up to November 2003) derived from searching the MEDLINE database with the keywords sublingual immunotherapy, respiratory allergy, asthma, and rhinitis. Sources included review articles, randomized controlled clinical trials, postmarketing surveillance studies, and relevant reports from meeting proceedings.

STUDY SELECTION

Articles concerning safety, efficacy, and mechanisms of SLIT published in English-language, peer-reviewed journals.

RESULTS

SLIT proved effective and safe in adults and children. As with traditional subcutaneous immunotherapy, SLIT has long-lasting efficacy and a preventive effect on new sensitizations.

CONCLUSION

SLIT is a viable alternative to subcutaneous immunotherapy. Its use in pediatric patients seems to be particularly promising.

Sublingual immunotherapy abrogates seasonal bronchial hyperresponsiveness in children with Parietaria-induced respiratory allergy: a randomized controlled trial

BACKGROUND

The use of immunotherapy in asthmatic children is still controversial. Sublingual immunotherapy (SLIT) may represent an advance, due to the good safety profile, but little is known about its effects on lung function and nonspecific bronchial responsiveness.

OBJECTIVE

The aim of this study was to assess the effects of SLIT on these parameters, in children with Parietaria pollen-induced asthma.

METHODS

Thirty children with asthma solely due to Parietaria who participated in a previous randomized, placebo-controlled trial with SLIT were studied: pulmonary function test and methacholine challenge were carried out at baseline in winter 1999 (out season), during the 1999 season (before randomization), and during the 2001 season.

RESULTS

Before randomization, there was a significant fall in methacholine provocation concentration during the pollen season vs baseline in both groups (SLIT group 9.78 +/- 5.95 mg/ml vs 3.37 +/- 2.99 mg/ml; placebo 8.70 +/- 6.25 mg/ml vs 2.44 +/- 2.25 mg/ml; P =.005). In the second pollen season, the response to methacholine returned to baseline values in the active group (9.10 +/- 7.7 mg/ml; P = NS vs baseline), whereas in the placebo group a significant increase in reactivity was still present (2.46 +/- 2.26; P = 0.008 vs baseline). No significant difference in FEV(1) and FEF(25-75) between the two groups was observed at all times.

CONCLUSIONS

Our data show that SLIT abrogates the seasonal bronchial hyperreactivity in children with asthma due to Parietaria. This may be regarded as an indirect evidence of the effect on bronchial inflammation.

Sublingual immunotherapy in asthma and rhinoconjunctivitis; systematic review of paediatric literature

AIMS

To evaluate the clinical efficacy of sublingual immunotherapy (SLIT) in respiratory allergy in children.

METHODS

A systematic literature review was conducted. The search was focused on all the double blind (and double dummy if necessary) studies.

SEARCH STRATEGY

Medline, Embase, Cochrane Controlled Trial Register, Abstract of Cochrane Airways Group, hand search, and archives of some SLIT producers. All the selected studies were assessed and evaluated for quality in a standardised independent way.

RESULTS

Eight randomised, double blind, placebo controlled studies on SLIT were selected. Five studies were run with house dust mite (HDM), one with olive pollen, one with wall pellitory (Parietaria) pollen, and one with grass pollen. A quantitative evaluation of the studies was not possible because the outcomes and the results of single studies were presented according to different criteria. Therefore only qualitative analysis was performed. No clinically relevant results were shown, independently from statistical significance, in the use of SLIT for respiratory allergies due to seasonal allergens (olive, wall pellitory, and grass pollens) and, on the whole, for rhinoconjunctivitis due to HDM in children. For mild to moderate persistent asthma due to HDM, statistically significant and low to moderate relevant clinical effects were observed.

CONCLUSIONS

SLIT can be currently considered to have low to moderate clinical efficacy in children of at least 4 years of age, monosensitised to HDM, and suffering from mild to moderate persistent asthma. This benefit seems to be adjunctive with respect to the environmental preventive measures against HDM.