Laura Sensi

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.

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.

Allergy and the gastrointestinal system

The gastrointestinal system plays a central role in immune system homeostasis. It is the main route of contact with the external environment and is overloaded every day with external stimuli, sometimes dangerous as pathogens (bacteria, protozoa, fungi, viruses) or toxic substances, in other cases very useful as food or commensal flora. The crucial position of the gastrointestinal system is testified by the huge amount of immune cells that reside within it. Indeed, gut‐associated lymphoid tissue (GALT) is the prominent part of mucosal‐associated lymphoid tissue (MALT) and represents almost 70% of the entire immune system; moreover, about 80% of plasma cells [mainly immunoglobulin A (IgA)‐bearing cells] reside in GALT. GALT interacts strictly with gastrointestinal functions in a dynamic manner; for instance, by increasing intestinal permeability in replay to particular stimulations, or orientating the immune response towards luminal content, allowing either tolerance or elimination/degradation of luminal antigens, or sometimes provoking damage to the intestinal mucosa, such as in coeliac disease or food allergy. The immune mechanisms implicated in these actions are very complex and belong to both innate and adaptive immunity; innate immunity supplies an immediate non‐specific response that is indispensable before specific adaptive immunity, which needs 7–10 days to be efficacious, takes place. The results of their interactions depend upon different contexts in which contact with external agents occurs and may change according to different genetic settings of the hosts.

Three-year follow-up of clinical and inflammation parameters in children monosensitized to mites undergoing sub-lingual immunotherapy

Parallel follow‐up of clinical and inflammatory markers during sub‐lingual immunotherapy (SLIT) is highly beneficial. Twenty‐four children (age 4–16) monosensitized to house dust mite were randomized to receive either active or placebo SLIT for 1 yr in a double‐blind placebo controlled design (Marcucci et al., Allergy 2003: 58: 657–62). Thereafter, for 2 yr they all received active treatment. Symptom scores for rhinitis, asthma, and drug usage were daily recorded. Eosinophil cationic proten (ECP) and tryptase in sputum and nasal secretions, serum and nasal mite‐specific immunoglobulin E (IgE) were recorded before treatment and at 10–12 months intervals. Nasal ECP and nasal tryptase after specific nasal provocation tests were significantly reduced as compared to baseline values (p = 0.0043 and 0.0195, respectively) in the third year of active treatment. None of the other inflammatory parameters was increased. In placebo treated patients all these parameters tended to decrease only after switching to active treatment. Clinical scores did not improve in treated vs. placebo patients in the double‐blind placebo‐controlled phase of the study. In both cohorts a clinical benefit was observed as intra‐group score reduction as compared to baseline. A significant difference was reached in patients treated for 2 yr for rhinitis and asthma (p = 0.0009 and 0.0019, respectively) but not for drug usage and in patients treated for 3 yr for rhinitis, asthma, and drug usage (p = 0.0105, 0.0048, and 0.02, respectively). SLIT in children monosensitized to mites reverted the spontaneous increase in nasal IgE and in local parameters of allergic inflammation. These outcomes were followed by a consolidated clinical improvement in the second and third year of treatment.

Dose dependence of immunological response to sublingual immunotherapy

Background:  Sublingual‐swallow immunotherapy (SLIT) is an accepted treatment for allergic rhinitis but its optimal dosage is scantly investigated. We studied the dose dependence of clinical efficacy and immunological response to SLIT by administering two different dosages of the same allergen in rhinitic children monosensitized to grass pollen.

Oral reactions to sublingual immunotherapy: a bioptic study.

glucocorticosteroids without the necessity for hospitalization. After resolution, the oral challenge test with a cephalosporin was well tolerated. Another amoxicillin patch test positive patient tolerated the oral challenge with penicillin, thereby revealing an isolated allergy to amoxicillin. As a challenge test would involve the risk for the patients to experience the same signs and symptoms of the previous drug reaction, the decision of four out of eight patients not to perform an oral challenge test was respected. Two of three patients, who were completely negative in the allergy diagnostic tests, agreed to an oral challenge with verum and revealed tolerance to the drug. It can be hypothesized that the third patch test negative subject may also have tolerated amoxicillin challenge. These three individuals may belong to the population, which only has a transient decrease in drug tolerance during EBV infection. Two amoxicillin patch test positive patients could be examined in a follow-up visit 2.2 and 1.5 years, respectively, after the first patch testing. Those patients revealed a patch test reaction similar in strength to the preliminary test result, which is indicative for a persistent delayed-type reaction to amoxicillin. In conclusion, this study does not only provide additional evidence that true delayed-type allergic reactions to aminopenicillins may develop during a florid viral infection, but that they may be definitely more prevalent than previously assumed and published (5, 6). Additionally, follow-up investigations on two patients revealed the persistence of the delayed-type reactions to amoxicillin, an approach, which has to the best of our knowledge not been published before. These observations should encourage the investigation of patients with aminopenicillin-induced exanthema for both, EBV-infection and true drug allergy. Particularly young women should be recommended an oral challenge with cephalosporins and maybe penicillins because the latter are antibiotics which may be given safely during pregnancy.

Specific IgE response to different grass pollen allergen components in children undergoing sublingual immunotherapy

BackgroundGrass pollen is a major cause of respiratory allergy worldwide and contain a number of allergens, some of theme (Phl p 1, Phl p 2, Phl p 5, and Phl 6 from Phleum pratense, and their homologous in other grasses) are known as major allergens. The administration of grass pollen extracts by immunotherapy generally induces an initial rise in specific immunoglobulin E (sIgE) production followed by a progressive decline during the treatment. Some studies reported that immunotherapy is able to induce a de novo sensitisation to allergen component previously unrecognized.MethodsWe investigated in 30 children (19 males and 11 females, mean age 11.3 years), 19 treated with sublingual immunotherapy (SLIT) by a 5-grass extract and 11 untreated, the sIgE and sIgG4 response to the different allergen components.ResultsSignificant increases (p < 0.001) were detected for Phl p 1, Phl p 2, Phl p 5, and Phl p 6, while sIgE levels induced in response to Phl p 7 and Phl p 12 were low or absent at baseline and unchanged following SLIT treatment; no new sensitisation was detected. As to IgG4, significant increases were found for Phl p2 and Phl p 5, while the increase for Phl p 12 was not significant. In the control group, no significant increase in sIgE for any single allergen component was found.ConclusionsThese findings confirm that the initial phase of SLIT with a grass pollen extract enhances the sIgE synthesis and show that the sIgE response concerns the same allergen components which induce IgE reactivity during natural exposure.

Safety of sublingual immunotherapy started during the pollen season

ABSTRACT Background: Sublingual immunotherapy (SLIT) is safer than subcutaneous immunotherapy (SCIT) and this has lead to the reconsideration of the use of ultra-rush schedules for SLIT. The aim of this study was to assess the safety of ultra-rush SLIT in pollen-allergic children according to different timing of administration in relation to the pollen season. Methods: In total, 34 children with pollen-induced rhinitis and 36 with pollen-induced asthma and rhinitis, were enrolled and assigned to three study groups: group 1 (n = 17 patients): conventional pre-seasonal-SLIT treatment; group 2 (n = 23 patients), seasonal SLIT ended before the pollen seasonal peak; group 3 (n = 30 patients), SLIT began after the pollen seasonal peak and ended after the pollen season. SLIT was performed using extracts from Stallergenes (Antony, France) and following an ultra-rush schedule, consisting in four doses at a 30-min intervals, and maintenance treatment by administering the top dose three times a week. Results: In all, 54 adverse events (AEs) were reported: 12 in nine patients in group 1 (9/17, 52.9%), 22 in 14 patients in group 2 (14/23, 60.9%), and 20 in 13 patients in group 3 (13/30, 43.3%). No statistically significant differences were found between the three groups. Local AEs (oral itching and burning) were short lasting and self-resolving. Systemic AEs were also mild, except for a case of asthma, which lasted 5 days, in a patient from group 1. There were no severe reactions, and none of the patients dropped out. Conclusions: This study suggests that SLIT with pollen extracts may be safely started at the beginning and also during the pollen season, with a tolerability profile comparable to the conventional pre-seasonal SLIT.

Which Allergen Extract for Grass Pollen Immunotherapy? an in Vitro Study

Background: Grass pollen is a major cause of allergy throughout the world. The only treatment targeting the causes and not only the symptoms of allergy is specific immunotherapy (IT). A number of controlled trials demonstrated the efficacy of IT in grass pollen allergic subjects, most using extracts of multiple grasses but some using extracts of a single grass. The optimal grass extract for IT has not yet been established. Methods: This study is aimed at investigating the IgE-binding pattern in sera from IT-naïve patients from central Italy with allergic rhinitis and/or asthma caused by grass pollen. A 5-grass extract was used (containing Dactylis glomerata, Poa pratensis, Lolium perenne, Antoxanthum odoratum and Phleum pratense) and compared to Phleum pratense alone, which is the most frequently used single grass extract, by the RAST-inhibition technique. Results: The 5-grass extract showed, by RAST-inhibition, a significantly higher binding compared to the Phleum pratense extract for Antoxanthum odoratum and Poa pratensis, while the two extracts for immunotherapy showed similar binding affinity for Phleum pratense and the non-Pooideae grass, Cynodon dactylon. Conclusions: The use of a mixed-grass pollen extract seems to be the optimal choice when applying specific IT in grass pollen-allergic subjects from the Mediterranean area.

Effects of Sublingual Immunotherapy on Allergic Inflammation: An Update

The most common allergic diseases, and especially the respiratory disorders such as rhinitis and asthma, are closely related to the allergic inflammation elicited by the causative allergen. This makes inflammation the main target of anti-allergic therapies. Among the available treatments, allergen specific immunotherapy (AIT) has a patent effect on allergic inflammation, which persists also after its discontinuation, and is the only therapy able to modify the natural history of allergy. The traditional, subcutaneous route of administration was demonstrated to modify the allergen presentation by dendritic cells (DCs) that in turn correct the phenotype of allergen-specific T cells, switching from the Th2-type response, typical of allergic inflammation and characterized by the production of IL-4, IL-5, IL-13, IL-17, and IL-32 cytokines to a Th1-type response. This immune deviation is related to an increased IFN-gamma and IL-2 production as well as to the anergy of Th2 or to tolerance, the latter being related to the generation of allergen-specific T regulatory (Treg) cells, which produce cytokines such as IL-10 and TGF-beta. Anti-inflammatory mechanisms observed during sublingual AIT with high allergen doses proved to be similar to subcutaneous immunotherapy. Data obtained from biopsies clearly indicate that the pathophysiology of the oral mucosa, with particular importance for mucosal DCs, plays a crucial role in inducing tolerance to the administered allergen.