Biochemical composition of Phleum pratense pollen grains: A review.

The Poaceae family is composed of 12,000 plant species. Some of these species produce highly allergenic anemophilous pollen grains (PGs). Phleum pratense pollen grains (PPPGs) emerged as a model for studies related to grass allergy. The biochemical composition of allergenic PGs has not yet been fully described despite potential health effects of PG constituents other than allergenic proteins. This review brings together the information available in literature aiming at creating a comprehensive picture of the current knowledge about the chemical composition of allergenic PGs from timothy grass. PPPGs have an average diameter between 30-35 µm and the mass of a single PG was reported between 11 and 26 ng. The pollen cytoplasm is filled with two types of pollen cytoplasmic granules (PCGs): the starch granules and the polysaccharide particles (p-particles). Starch granules have a size between 0.6-2.5 µm with an average diameter of 1.1 µm (estimated number of 1000 granules per PG) while p-particles have a size ranging around 0.3 to 0.4 µm (estimated number between 61,000-230,000 p-particles per PG). The rupture of PG induces the release of PCGs and the dispersion of allergens in the inhalable fraction of atmospheric aerosol. PPPGs are composed of sporopollenin, sugars, polysaccharides, starch, glycoproteins (including allergens), amino-acids, lipids, flavonoids (including isorhamnetin), various elements (the more abundant being Si, Mg and Ca), phenolic compounds, phytoprostanoids, carotenoids (pigments) metals and adsorbed pollutants. PPPG contains about a hundred different proteins with molecular masses ranging from 10 to 94 kDa, with isoelectric points from 3.5-10.6. Among these proteins, allergens are classified in eleven groups from 1 to 13 with allergens from groups 1 and 5 being the major contributors to Phl p pollen allergy. Major allergen Phl p 5 was quantified in PPPGs by several studies with concentration ranging from 2.7 and 3.5 µg.mg-1 in unpolluted environment. Values for other allergens are scarce in literature; only one quantitative assessment exists for allergen groups Phl p 1, 2 and 4. The extractible lipid fraction of PPPGs is estimated between 1.7-2.2% of the total PG mass. The main chemical families of lipids reported in PPPGs are: alkanes, alkenes, alcohols, saturated and unsaturated fatty acids, di- and tri-hydroxylated fatty acids, aldehydes and sterols. Several lipid compounds with potential adjuvant effects on allergy have been specifically quantified in PPPGs: E2-like prostaglandin (PGE2), B4-like leukotriene (LTB4), unsaturated fatty acids (linoleic and linolenic acids and their hydroxylated derivatives), adenosine, vitamins and phenolic compounds. Some other biochemical characteristics such as NAD(P)H oxidase, protease activity and pollen microbiome were described in the literature. The bioaccessibility in physiological conditions has not been described for most biochemicals transported by allergenic PPPGs. There is also a considerable lack of knowledge about the potential health effects of pollen constituents other than allergens. The variability of pollen composition remains also largely unknown despite its importance for plant reproduction and allergy in an environment characterized by chemical pollution, climate change and loss of biodiversity.

Differential induction of allergen-specific IgA responses following timothy grass subcutaneous and sublingual immunotherapy.

INTRODUCTION: There is no detailed comparison of allergen-specific immunoglobulin responses following sublingual immunotherapy (SLIT) and subcutaneous immunotherapy (SCIT). OBJECTIVE: We sought to compare nasal and systemic timothy grass pollen (TGP)-specific antibody responses during 2 years of SCIT and SLIT and 1 year after treatment discontinuation in a double-blind, double-dummy, placebo-controlled trial. METHODS: Nasal fluid and serum were obtained yearly (per-protocol population, n = 84). TGP-specific IgA1, IgA2, IgG4, IgG, and IgE were measured in nasal fluids by ELISA. TGP-specific IgA1, IgA2, and Phleum pratense (Phl p)1, 2, 4, 5b, 6, 7, 11, and 12 IgE and IgG4 were measured in sera by ELISA and ImmunoCAP, respectively. RESULTS: At years 2 and 3, TGP-IgA1/2 levels in nasal fluid were elevated in SLIT compared with SCIT (4.2- and 3.0-fold for IgA1, 2.0- and 1.8-fold for IgA2, respectively; all P < .01). TGP-IgA1 level in serum was elevated in SLIT compared with SCIT at years 1, 2, and 3 (4.6-, 5.1-, and 4.7-fold, respectively; all P < .001). Serum TGP-IgG level was higher in SCIT compared with SLIT (2.8-fold) at year 2. Serum TGP-IgG4 level was higher in SCIT compared with SLIT at years 1, 2, and 3 (10.4-, 27.4-, and 5.1-fold, respectively; all P < .01). Serum IgG4 levels to Phl p1, 2, 5b, and 6 were increased at years 1, 2, and 3 in SCIT and SLIT compared with placebo (Phl p1: 11.8- and 3.9-fold; Phl p2: 31.6- and 4.4-fold; Phl p5b: 135.5- and 5.3-fold; Phl p6: 145.4- and 14.7-fold, respectively, all at year 2 when levels peaked; P < .05). IgE to TGP in nasal fluid increased in the SLIT group at year 2 but not at year 3 compared with SCIT (2.8-fold; P = .04) and placebo (3.1-fold; P = .02). IgA to TGP and IgE and IgG4 to TGP components stratified participants according to treatment group and clinical response. CONCLUSIONS: The observed induction of IgA1/2 in SLIT and IgG4 in SCIT suggest key differences in the mechanisms of action.

Crystal structure of timothy grass allergen Phl p 12.0101 reveals an unusual profilin dimer.

Timothy grass pollen is a source of potent allergens. Among them, Phl p 1 and Phl p 5 are thought to be the most important, as a majority of timothy grass-allergic individuals have IgE antibodies directed against these two allergens. The profilin from timothy grass (Phl p 12) has been registered as a minor allergen, with up to 35% of individuals in populations of grass pollen allergic patients showing IgE binding to Phl p 12. Profilins are primarily minor allergens and are known for a high likelihood of co-sensitization as well as cross-reactivity situations caused by their sequence and structure similarity. The crystal structure of Phl p 12.0101 was determined and it revealed that this allergen may form an unusual dimer not previously observed among any profilins. For example, the Phl p 12 dimer has a completely different geometry and interface when compared with the latex profilin (Hev b 8) dimer that has its crystal structure determined. The structure of Phl p 12.0101 is described in the context of allergenic sensitization and allergy diagnostics. Moreover, the structure of the Phl p 12.0101 dimer is discussed, taking into account the production of recombinant allergens and their storage.

Allergenicity at component level of sub-pollen particles from different sources obtained by osmolar shock: A molecular approach to thunderstorm-related asthma outbreaks.

BACKGROUND: The so-called "thunderstorm asthma" (TA) is an uncommon but dramatic outbreak of asthma attacks occurring during a thunderstorm in the pollen and moulds season. Mechanisms which make the pollen able to enter the deeper airways and provoke severe asthma symptoms are still unclear. OBJECTIVE: To test the hypothesis that sub-pollen particles (SPPs) originated from the rupture by an osmotic shock of pollen associated with TA contain allergens. METHODS: After hydration, SPPs released from pollen grains of grass, pellitory, olive, cypress, ragweed and birch were isolated and determined by microscopy. Allergens were determined by in vitro ELISA inhibition tests indirectly using the sera from 10 polyreactive patients. An inhibition <50% was considered as negative, 50%-75% moderate and > 75% complete. RESULTS: The inhibition experiments showed that the SPPs from birch and cypress were unable to inhibit serum IgE reactivity to Bet v 1 and Cup a 1, respectively. Ragweed SPPs inhibited ragweed pollen extract and Amb a 1 by 75.8 ± 0.11% and 81.2 ± 0.15%, respectively. Olive and pellitory SPPs retained almost the whole IgE-binding capability in all cases tested. Grass SPPs inhibited 32 ± 0.06% of Lolium perenne Lol p 1 and 65% of Phleum pratense extracts, but results were highly variable for individual allergens (97.5%-0.03% for Phl p 2, 45.3 ± 0.12% for Phl p 5, 24.7 ± 0.22% for Phl p 6, and 38.3 ± 0.2% for Phl p 1). CONCLUSIONS: Inhibition experiments confirm the hypothesis that SSPs obtained after the osmotic shock of pollen involved in TA, namely grass, pellitory and olive tree pollen, contain allergens and therefore they can induce severe asthma attacks during thunderstorms.

IL-31 transgenic mice show reduced allergen-induced lung inflammation.

Interleukin-31 (IL-31) is a Th2 cell-derived cytokine that has been closely linked to pruritic skin inflammation. More recently, enhanced IL-31 serum levels have also been observed in patients with allergic rhinitis and allergic asthma. Therefore, the main aim of this study was to unravel the contribution of IL-31 to allergen-induced lung inflammation. We analyzed lung inflammation in response to the timothy grass (Phleum pratense) pollen allergen Phl p 5 in C57BL/6 wild-type (wt) mice, IL-31 transgenic (IL-31tg) mice, and IL-31 receptor alpha-deficient animals (IL-31RA-/- ). IL-31 and IL-31RA levels were monitored by qRT-PCR. Cellular infiltrate in bronchoalveolar lavage fluid (BALF) and lung tissue inflammation, mucus production as well as epithelial thickness were measured by flow cytometry and histomorphology. While allergen challenge induced IL-31RA expression in lung tissue of wt and IL-31tg mice, high IL-31 expression was exclusively observed in lung tissue of IL-31tg mice. Upon Phl p 5 challenge, IL-31tg mice showed reduced numbers of leukocytes and eosinophils in BALF and lung tissue as well as diminished mucin expression and less pronounced epithelial thickening compared to IL-31RA-/- or wt animals. These findings suggest that the IL-31/IL-31RA axis may regulate local, allergen-induced inflammation in the lungs.

Intradermal Phleum pratense allergoid immunotherapy. Double-blind, randomized, placebo-controlled trial.

BACKGROUND: In allergology, the intradermal approach is generally used to establish an aetiological diagnosis, with limited experience in specific allergen immunotherapy. OBJECTIVE: To evaluate the efficacy and safety of immunotherapy with an allergen extract of glutaraldehyde-polymerized Phleum pratense, administered intradermally, in patients with rhinoconjunctivitis sensitized to grass pollen. METHODS: Multicentre, randomized, double-blind, placebo-controlled clinical trial in patients from 12 to 65 years of age with rhinitis or rhinoconjunctivitis, with or without asthma, due to grass pollen allergy. Patients were divided into three groups and received a total of six doses in a weekly interval, of either placebo; 0.03 or 0.06 µg of protein per dose of P pratense allergoid. The primary objective was to evaluate the combined symptoms and medication consumption score (CSMS). The secondary objectives were symptoms and medication, tolerance to the conjunctival provocation test, specific IgE and IgG4 antibodies and the safety profile according to the WAO scale. RESULTS: The dose of 0.06 µg of protein proved to be effective versus the placebo by significantly reducing CSMS and increasing tolerance to the allergenic extract in the conjunctival provocation test, after the first pollen season. This group showed a significant reduction in specific IgE after the second pollen season relative to the baseline. There were no variations in IgG4 levels. Only one grade 2 systemic reaction was recorded. CONCLUSION & CLINICAL RELEVANCE: Intradermal immunotherapy with P pratense allergoid has been shown to be effective and safe, reducing CSMS, increasing tolerance to the conjunctival provocation test and reducing IgE levels.

Nasal reactivity evaluation in children with allergic rhinitis receiving grass pollen sublingual immunotherapy.

Background: The European Academy of Allergy and Clinical Immunology guidelines, strongly recommended allergen immunotherapy (AIT) as an effective treatment to achieve long-term clinical benefits and to modify the natural history of allergic diseases. Sublingual immunotherapy (SLIT) offers the possibility of home administration, which improves patient comfort and compliance. Objective: The primary outcome of this study was to assess the change in nasal reactivity after grass-pollen AIT treatment. Methods: This was a monocentric, prospective, observational study conducted in Rome from September 2016 to June 2018, in the Pediatric Department of Policlinico Umberto I. We enrolled children, ages between 6 and 12 years, with persistent allergic rhinitis (AR), sensitized to grass pollen. At the first visit (V0, September 2016), one group received the first dose of oral immunotherapy for grass-pollen spray buccal and the other group continued only standard therapy. All the patients had nasal specific immunoglobulin I (IgE) assay (Phl p1, Phl p5), active anterior rhinomanometry with a nasal provocation test (NPT), and spirometry. The patients attended two follow-up visits, in May 2017 (V1) and May 2018 (V2), with the same examinations as at V0. Results: During the treatment, we observed, in the treated group, a significant increase in the mean nasal flow compared with untreated children (p < 0.001). In the AIT group, we found an improvement of nasal function and only 21.05% of all the children in the active group with a positive NPT result at V2. In the control group, we found, at V2, a worsening of nasal function, with 89.47% of the children with a positive NPT result. Furthermore, we found a significant reduction of nasal specific IgE levels at the end of the observation period in the treated group. Conclusion: Analysis of our data provided evidence for a clinical effect of SLIT in inducing clinical changes and allergen tolerance in children with AR.

Serum immunoglobulin E reactivity to cross-reacting panallergen components in north-eastern Poland patients pollen sensitized.

Background: The presence of immunoglobulin E (IgE), which cross-reacts with allergen components, such as profilins, polcalcins, and cross-reacting carbohydrate determinants (CCD), creates a problem when selecting patients for allergen immunotherapy by using conventional methods. The aim of this study was to evaluate the prevalence of sensitization to profilins, polcalcins, and CCDs in patients with seasonal pollen allergic rhinitis. Methods: The study was performed on a group of 112 patients with seasonal pollen allergic rhinitis, ages 14 to 55 years, with sensitization to at least one seasonal allergen (IgE > 0.7 kUA/L). The presence of IgE sensitization to recombinant (r) Bet v 2, rPhl p 12, rBet v 4, rPhl p 7, and CCDs, in addition to rBet v 1, rPhl p 1, rPhl p 5, was evaluated by using a multiparameter immunoblot. Results: Among the studied patients, 64.3, 80.4, and 41.1% were sensitized to birch, timothy grass, and mugwort pollen, respectively. Sensitization to profilins rBet v 2/Phl p 12 was demonstrated in 28.6%, to polcalcins Bet v 4/Phl p 7 in 8.9%, and to CCDs in 25%. In 29.3%, serum IgE reactivity to any of the cross-reactive components could be demonstrated. Serum IgE reactivity to rBet v 2 was always accompanied by IgE reactivity to rPhl p 12, and IgE reactivity to rBet v 4 was always accompanied by IgE reactivity to rPhl p 7. Among the patients with pollinosis co-sensitized to at least two allergen sources according to extract-based diagnosis, possible false-positive results due to sensitization to cross-reactive components were detected in 17.9%. Conclusion: Evaluation of sensitization to cross-reacting components may be useful in evaluation of patients with pollen allergy who are being assessed for allergen immunotherapy to optimize the constitution of their immunotherapy vaccines.

Peach Tree Pollen and Prunus persica 9 Sensitisation and Allergy in Children and Adolescents.

BACKGROUND: Although plant and fruit pollens are entomophilous and relevant in exposed workers, we have shown a high frequency of sensitisation and symptoms induction of peach tree pollen (PTP) and Prunus persica 9 (Pru p 9) in adults from areas of peach cultivars. METHODS: We studied the sensitisation and clinical relevance of PTP and Pru p 9 in a large group of children and adolescents aged 3-19 years. A detailed questionnaire plus skin prick testing to prevalent allergens, PTP, and Pru p 9 were carried out. The clinical relevance was established by nasal provocation test (NPT) and symptom score index. RESULTS: We evaluated 685 children (mean age 8.75 ± 3.3 years, median 9 years), 52% of them female. Sensitisation to PTP occurred in 20% of the cases following olive tree (33%) and Phleum pratense (26%). In a randomly selected subgroup of subjects sensitised to PTP, 30% were skin prick test-positive to Pru p 9. Most cases had rhinitis or rhinoconjunctivitis. NPT showed the relevance of PTP and Pru p 9 in the induction of symptoms. CONCLUSION: PTP and Pru p 9 are relevant in the induction of sensitisation and respiratory symptoms in children and adolescents. This allergen should be evaluated in children living in regions of peach tree cultivars.

Tolerability and surrogate efficacy parameters of a polymerized depot mixture pollen extracts without dilutional effect.

Aim: To evaluate tolerability of subcutaneous immunotherapy, in a polymerized mixture (Olea europaea/Phleum pratense) depot presentation. Patients & methods: A total of 47 poly-allergic patients received: an abbreviated schedule with three injections at weekly intervals or a cluster schedule with two administrations in 1 day. Both treatments continued with 3 monthly maintenance administrations. Results: Two systemic reactions, (4.3%). One grade 0 and one grade I. No local reactions. Immunoglobulin levels, increased significantly at final visit versus baseline in sIgG and sIgG4; in both schedules and allergens, no significant changes in specific immunoglobulin E levels were detected. Cutaneous reactivity at final visit decreased significantly. Conclusion: Both administration schedules with polymerized mixture of O. europaea/P. pratense, presented an excellent tolerability profile and induced preliminary efficacy changes.

Lipid Mediators From Timothy Grass Pollen Contribute to the Effector Phase of Allergy and Prime Dendritic Cells for Glycolipid Presentation.

Plant pollen are an important source of antigens that evoke allergic responses. Protein antigens have been the focus of studies aiming to elucidate the mechanisms responsible for allergic reactions to pollen. However, proteins are not the sole active agent present in pollen. It is known that pollen grains contain lipids essential for its reproduction and bioactive lipid mediators. These small molecular compounds are co-delivered with the allergens and hence have the potential to modulate the immune response of subjects by activating their innate immune cells. Previous reports showed that pollen associated lipid mediators exhibited neutrophil- and eosinophil-chemotactic activity and induced polarization of dendritic cells (DCs) toward a Th2-inducing phenotype. In our study we performed chemical analyses of the pollen associated lipids, that are rapidly released upon hydration. As main components we have identified different types of phytoprostanes (PhytoPs), and for the first time phytofurans (PhytoFs), with predominating 16-F1t-PhytoPs (PPF1-I), 9-F1t-PhytoPs (PPF1-II), 16-E1t-PhytoPs (PPE1-I) and 9-D1t-PhytoPs (PPE1-II), and 16(RS)-9-epi-ST-Δ14-10-PhytoFs. Interestingly 16-E1t-PhytoP and 9-D1t-PhytoPs were found to be bound to glycerol. Lipid-containing samples (aqueous pollen extract, APE) induced murine mast cell chemotaxis and IL-6 release, and enhanced their IgE-dependent degranulation, demonstrating a role for these lipids in the immediate effector phase of allergic inflammation. Noteworthy, mast cell degranulation seems to be dependent on glycerol-bound, but not free phytoprostanes. On murine dendritic cells, APE selectively induced the upregulation of CD1d, likely preparing lipid-antigen presentation to iNKT cells. Our report contributes to the understanding of the activity of lipid mediators in the immediate effector phase of allergic reactions but identifies a yet undescribed pathway for the recognition of pollen-derived glycolipids by iNKT cells.

The Clinical Relevance of Natural Rubber Latex-Specific IgE in Patients Sensitized to Timothy Grass Pollen.

BACKGROUND: In pollen-allergic patients, cross-reacting allergens including cross-reactive carbohydrate determinants (CCDs) and profilins may result in positive natural rubber latex (NRL)-specific IgE (sIgE) antibody tests but the relationship between this sensitization and clinical NRL type 1 allergy is poorly described. OBJECTIVE: The aims of this study were to determine the frequency and clinical relevance of NRL sIgE in grass pollen-sensitized individuals and to investigate which NRL allergen components these individuals were sensitized to. METHODS: A total of 383 grass-sensitized patients answered questions about NRL allergy symptoms and their stored sera from previous investigations were analyzed for NRL sIgE. Patients with NRL sIgE (n = 32) underwent further investigations comprising medical history, skin prick test with NRL and inhalational allergens, and an additional blood sample. The additional blood samples were analyzed for total IgE and sIgE against NRL, timothy grass, birch, rHev b 1, 3, 5, 6.01, 6.02, 8, 9, 11, rPhl p 12, and MUXF3, which was used as a marker of CCD sensitization. RESULTS: Overall, 9.4% of all grass pollen-sensitized individuals showed IgE sensitization to NRL but only 1.6% had a confirmed type I NRL allergy. CCD and Hev b 8 explained the clinically irrelevant NRL IgE sensitization in 65% of the cases. We found a highly significant correlation between NRL profilin (Hev b 8) sensitization and grass profilin (Phl p 12) sensitization (p < 0.0001). CONCLUSIONS: Data from this study support the hypothesis that in patients with grass pollen sensitization, Hev b 8 mono-sensitization has little or no clinical relevance and is caused by cross sensitization from grass profilin (Phl p 12).

Sublingual immunotherapy alters salivary IgA and systemic immune mediators in timothy allergic children.

BACKGROUND: Immunomodulatory effects of sublingual immunotherapy on systemic and mucosal mediators in allergic children are largely unexplored. The aim of this study was to investigate allergy-related cytokine and chemokine levels, as well as IgA-responses upon a 3-year treatment with timothy grass pollen sublingual immunotherapy in children with allergic rhinoconjunctivitis. METHODS: From children included in the GRAZAX® Asthma Prevention study, blood and saliva samples were analyzed at inclusion, after 3 years of treatment, and 2 years after treatment ending. By means of Luminex and ELISA methodologies, allergy-related cytokines and chemokines were measured in plasma samples and allergen-stimulated peripheral blood mononuclear cell supernatants. Furthermore, studies of total, secretory, and Phl p 1-specific salivary IgA antibodies were performed using the same methods. RESULTS: GRAZAX® -treated children exhibited significantly higher levels of Phl p 1-specific salivary IgA and serum IgG4 , along with significantly lower skin prick test positivity, after 3 years of treatment and 2 years after treatment cessation. Additionally, plasma levels of the Th1-associated chemokines CXCL10 and CXCL11 were significantly higher in treated than untreated children at these time points. Timothy-induced ratios of IL-5/IL-13 over IFN-γ were significantly decreased after 3 years with active treatment, as were symptoms of allergic rhinitis in terms of both severity and visual analogue scale scores. However, no consistent correlations were found between the clinical outcomes and immunologic parameters. CONCLUSION: Phleum pratense sublingual immunotherapy in grass pollen allergic children modulates the immune response in the oral mucosa as well as systemically-by increasing Th1-responses, decreasing Th2-responses, and inducing immunoregulatory responses-all signs of tolerance induction.

Nasal allergen-neutralizing IgG4 antibodies block IgE-mediated responses: Novel biomarker of subcutaneous grass pollen immunotherapy.

BACKGROUND: Grass pollen subcutaneous immunotherapy (SCIT) is associated with induction of serum IgG4-associated inhibitory antibodies that prevent IgE-facilitated allergen binding to B cells. OBJECTIVE: We sought to determine whether SCIT induces nasal allergen-specific IgG4 antibodies with inhibitory activity that correlates closely with clinical response. METHODS: In a cross-sectional controlled study, nasal fluid and sera were collected during the grass pollen season from 10 SCIT-treated patients, 13 untreated allergic patients (with seasonal allergic rhinitis [SAR]), and 12 nonatopic control subjects. Nasal and serum IgE and IgG4 levels to Phleum pratense components were measured by using the Immuno Solid Allergen Chip microarray. Inhibitory activity was measured by IgE-facilitated allergen binding assay. IL-10+ regulatory B cells were quantified in peripheral blood by using flow cytometry. RESULTS: Nasal and serum Phl p 1- and Phl p 5-specific IgE levels were increased in patients with SAR compared to nonatopic control subjects (all, P < .001) and SCIT-treated patients (nasal, P < .001; serum Phl p 5, P = .073). Nasal IgG4 levels were increased in the SCIT group compared to those in the SAR group (P < .001) during the pollen season compared to out of season. IgG-associated inhibitory activity in nasal fluid and serum was significantly increased in the SCIT group compared to that in the SAR (both, P < .01). The magnitude of the inhibitory activity was 93% (P < .001) in nasal fluid compared to 66% (P < .001) in serum and was reversed after depletion of IgG. Both nasal fluid (r = -0.69, P = .0005) and serum (r = -0.552, P = .0095) blocking activity correlated with global symptom improvement. IL-10+ regulatory B cells were increased in season compared to out of season in the SCIT group (P < .01). CONCLUSION: For the first time, we show that nasal IgG4-associated inhibitory activity correlates closely with the clinical response to allergen immunotherapy in patients with allergic rhinitis with or without asthma.

Lack of effect of Timothy grass pollen sublingual immunotherapy tablet on birch pollen-induced allergic rhinoconjunctivitis in an environmental exposure unit.

BACKGROUND: Timothy grass pollen allergen extract tablets (Grastek) are standardized sublingual immunotherapy tablets (SLIT-T) approved for the treatment of grass pollen-induced allergic rhinitis (AR) and conjunctivitis. Many grass allergic patients are also cosensitized to birch pollen. Whether Timothy grass SLIT-T can confer symptomatic benefits for birch pollen-induced AR symptoms is unknown. OBJECTIVE: To evaluate the treatment effect of Timothy grass SLIT-T for birch pollen-induced AR in participants sensitized to both grass and birch pollen using an environmental exposure unit (EEU). METHODS: This study was a phase 4, randomized, double-blind, placebo-controlled, parallel-group study that enrolled participants aged 18 to 65 years allergic to both timothy grass and birch pollen. After a baseline EEU birch pollen challenge, in which a minimum total nasal symptom score (TNSS) of 6 of 12 was required for enrollment, participants were randomized to receive Timothy grass SLIT-T or placebo taken once daily for 4 months. No confirmatory grass pollen challenge was performed. The primary end point was the change in TNSS averaged from assessments from hours 2 to 5 during the posttreatment birch pollen challenge compared with baseline. The secondary and exploratory end points included temporally identical changes in total ocular symptom score (TOSS), total rhinoconjunctivitis symptom score (TRSS), and individual symptom scores. RESULTS: The difference in TNSS reduction after 4 months of therapy between the Timothy grass SLIT-T and placebo group was not significant (P = .83). Reductions in TOSS (P = .19) and TRSS (P = .67) were also comparable between groups. Findings between groups for individual symptom scores were similar (all P > .40), except for watery eyes, in which symptom reduction was slightly better in the placebo arm (P = .01). Timothy grass SLIT-T was well tolerated, and no serious adverse effects occurred. CONCLUSION: A bystander effect of grass SLIT-T on birch pollen-induced AR symptoms was not detected. Symptomatic benefits of grass SLIT-T are likely allergen specific. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02394600.

Synchronous immune alterations mirror clinical response during allergen immunotherapy.

BACKGROUND: Three years of treatment with either sublingual or subcutaneous allergen immunotherapy has been shown to be effective and to induce long-term tolerance. The Gauging Response in Allergic Rhinitis to Sublingual and Subcutaneous Immunotherapy (GRASS) trial demonstrated that 2 years of treatment through either route was effective in suppressing the response to nasal allergen challenge, although it was insufficient for inhibition 1 year after discontinuation. OBJECTIVE: We sought to examine in the GRASS trial the time course of immunologic changes during 2 years of sublingual and subcutaneous immunotherapy and for 1 year after treatment discontinuation. METHODS: We performed multimodal immunomonitoring to assess allergen-specific CD4 T-cell properties in parallel with analysis of local mucosal cytokine responses induced by nasal allergen exposure and humoral immune responses that included IgE-dependent basophil activation and measurement of serum inhibitory activity for allergen-IgE binding to B cells (IgE-facilitated allergen binding). RESULTS: All 3 of these distinct arms of the immune response displayed significant and coordinate alterations during 2 years of allergen desensitization, followed by reversal at 3 years, reflecting a lack of a durable immunologic effect. Although frequencies of antigen-specific TH2 cells in peripheral blood determined by using HLA class II tetramer analysis most closely paralleled clinical outcomes, IgE antibody-dependent functional assays remained inhibited in part 1 year after discontinuation. CONCLUSION: Two years of allergen immunotherapy were effective but insufficient for long-term tolerance. Allergen-specific TH2 cells most closely paralleled the transient clinical outcome, and it is likely that recurrence of the T-cell drivers of allergic immunity abrogated the potential for durable tolerance. On the other hand, the persistence of IgE blocking antibody 1 year after discontinuation might be an early indicator of a protolerogenic mechanism.

Phleum pratense molecular pattern across Italy.

SUMMARY: Introduction. Phleum pratense (Timothy grass) is the most frequent cause of grass allergy in Europe. Molecular-based allergy diagnostics have been recently introduced in the clinical practice, allowing to define and characterize exactly the sensitization profile. Aim of the study. The present study was aimed to investigate the possible relationships between Graminaceae pollen data and the pattern of IgE reactivity to different allergen components across Italy. Methods. Pollen data, including duration and quantity, were recorded over a 10-year period in 24 Italian centres located along the Italian peninsula. Phl p molecular patterns (Phl p 1, 5, 7, 12) were evaluated in 4 different Italian geographical areas. Results. There were significant differences about pollen count and sensitization prevalence across Italy. Different molecular patterns were defined considering the different Italian locations. Conclusion. This study demonstrates that Phleum pratense sensitization is relevant in Italy, but there are significant geographical variations variations as far as pollen exposure and pattern of IgE reactivity to the considered allergen components are concerned. This information may have clinical relevance in managing patients allergic to grass pollen.