Kaare Lund

Functional rather than immunoreactive levels of IgG4 correlate closely with clinical response to grass pollen immunotherapy

To cite this article: Shamji MH, Ljørring C, Francis JN, Calderon MA, Larché M, Kimber I, Frew AJ, Ipsen H, Lund K, Würtzen PA, Durham SR. Functional rather than immunoreactive levels of IgG4 correlate closely with clinical response to grass pollen immunotherapy. Allergy 2012; 67: 217–226.

Phl p 5 resorption in human oral mucosa leads to dose-dependent and time-dependent allergen binding by oral mucosal Langerhans cells, attenuates their maturation, and enhances their migratory and TGF-β1 and IL-10–producing properties

BACKGROUND Sublingual immunotherapy (SLIT) is safe and effective as treatment of allergic rhinitis and mild asthma. Oral mucosal Langerhans cells (oLCs) play a central role. However, little is known about allergen binding by oLCs during mucosal allergen resorption and its impact on oLC functions. OBJECTIVE Binding of Phl p 5 to oLCs was studied in a standardized ex vivo model to investigate mechanisms important for SLIT. METHODS Human oral mucosal biopsies were incubated with the grass pollen allergen Phl p 5. Migration, binding of Phl p 5, phenotype and cytokine production, and T-cell priming of Phl p 5-binding oLCs were analyzed. RESULTS Significant uptake required more than 5 minutes, and dose-dependent binding of Phl p 5 to oLCs was saturated at 100 microg/mL Phl p 5. Furthermore, Phl p 5 significantly increased the migratory capacity of oLCs but attenuated their maturation and strongly promoted the release of TGF-beta1 and IL-10 by oLCs themselves as well as by cocultured T cells. CONCLUSION Oral mucosal Langerhans cells bind Phlp5 in a dose-dependent and time-dependent manner, leading to an increased production of tolerogenic cytokines and an enhanced migratory capacity but decelerated maturation of oLCs.

A double-blind placebo-controlled birch allergy vaccination study II: correlation between inhibition of IgE binding, histamine release and facilitated allergen presentation

Background The pathogenesis of IgE‐mediated allergic disease is closely related to the production of T‐helper type 2 (Th2) cytokines, which lead to IgE production pivotal for activation of mast cells and basophils. Proliferating T cells along with eosinophils expanded and attracted by Th2 cytokines are major contributors to the late‐phase reaction. The activation of these Th2 cells is strongly enhanced by CD23‐mediated IgE facilitated allergen presentation (FAP).

The Crystal Structure of Recombinant proDer p 1, a Major House Dust Mite Proteolytic Allergen

Allergy to house dust mite is among the most prevalent allergic diseases worldwide. Most house dust mite allergic patients react to Der p 1 from Dermatophagoides pteronyssinus, which is a cysteine protease. To avoid heterogeneity in the sample used for crystallization, a modified recombinant molecule was produced. The sequence of the proDer p 1 allergen was modified to reduce glycosylation and to abolish enzymatic activity. The resulting rproDer p 1 preparation was homogenous and stable and yielded crystals diffracting to a resolution of 1.61 Å. The active site is located in a large cleft on the surface of the molecule. The 80-aa pro-peptide adopts a unique fold that interacts with the active site cleft and a substantial adjacent area on the mature region, excluding access to the cleft and the active site. Studies performed using crossed-line immunoelectrophoresis and IgE inhibition experiments indicated that several epitopes are covered by the pro-peptide and that the epitopes on the recombinant mature molecule are indistinguishable from those on the natural one. The structure confirms previous results suggesting a preference for aliphatic residues in the important P2 position in substrates. Sequence variations in related species are concentrated on the surface, which explains the existence of cross-reacting and species-specific antibodies. This study describes the first crystal structure of one of the clinically most important house dust mite allergens, the cysteine protease Der p 1.

Optimisation of grass pollen nasal allergen challenge for assessment of clinical and immunological outcomes.

Nasal allergen challenge can be used to assess the clinical and immunological aspects of rhinitis due to inhalant allergens. We aimed to develop a reproducible technique for grass pollen nasal allergen challenge and to study biomarkers within nasal secretions. 20 Grass pollen allergic individuals underwent nasal challenges with purified Timothy grass allergen. An initial dose-titration challenge was used to determine dose-response characteristics. Subsequently, volunteers underwent 3 further challenges using individualised threshold doses. Symptom scores, visual analogue scores, and peak nasal inspiratory flow (PNIF) were recorded at baseline and up to 6h after challenge. Nasal secretions were collected at each time point using synthetic filter papers or absorptive polyurethane sponges and analysed for IL-4, -5, -10, -13, IFN-γ, Tryptase and Eosinophil Cationic Protein (ECP). Challenges gave reproducible symptom scores and decreased PNIF. Tryptase levels in nasal fluid peaked at 5 min after challenge and returned to baseline levels at 1h. ECP, IL-5, IL-13 and IL-4 levels were increased from 2-3 h and showed progressive increases to 5-6 h. Sponges proved the superior nasal fluid sampling technique. We have developed a reproducible nasal allergen challenge technique. This may be used as a surrogate clinical endpoint in trials assessing the efficacy of treatments for allergic rhinitis. Tryptase in local nasal secretions is a potential biomarker of the early phase response; ECP and the Th2 cytokines IL-5, -13 and -4 markers of late phase allergic responses. Our model allows correlation between clinical responses and local biomarkers following nasal allergen challenge.

Sublingual immunotherapy reduces allergic symptoms in a mouse model of rhinitis.

Background Sublingual immunotherapy (SLIT) is a clinically effective treatment in both pollen and house dust mite‐induced rhinitis and asthma. However, the mechanisms by which this is accomplished are not clear.

Sublingual immunotherapy in sensitized mice

BACKGROUND Many studies have demonstrated immunologic changes induced by sublingual immunotherapy (SLIT), but the definitive mechanism of action needs further investigation. OBJECTIVE To study the immunologic response induced by SLIT in sensitized mice. METHODS Timothy grass (Phleum pratense)-sensitized mice received SLIT for 2, 4, or 6 weeks at 3 different concentrations, including a buffer control. Serum samples and washes of the lungs (bronchoalveolar lavage [BAL]) and the nasal passages (nasal lavage [NAL]) were analyzed for allergen-specific antibodies. T cells were isolated from the spleen and cervical lymph nodes for the analysis of proliferation and cytokine production. RESULTS Sublingual immunotherapy in sensitized mice resulted in a 30-fold increase in antigen specific IgA levels in BAL and NAL fluid compared with buffer-treated mice, whereas antigen specific IgE was undetectable in BAL and NAL fluid in animals treated with SLIT. Furthermore, IgA levels were proportional to the dose and duration of SLIT. Levels of specific IgA in serum correlated with levels in BAL and NAL fluid. Serum IgA levels were proportional to the duration of allergen exposure to the oral mucosa. Conversely, no changes in serum levels of IgE and IgG were induced by SLIT. Proliferation of T cells was increased in mice treated with SLIT compared with nontreated mice. CONCLUSION High levels of IgA in serum and in BAL and NAL fluid of mice treated with SLIT demonstrate that SLIT induces a mucosal, nonallergic response in sensitized mice.

Structure of the house dust mite allergen Der f 2: implications for function and molecular basis of IgE cross-reactivity.

The X‐ray structure of the group 2 major allergen from Dermatophagoides farinae (Der f 2) was determined to 1.83 Å resolution. The overall Der f 2 structure comprises a single domain of immunoglobulin fold with two anti‐parallel β‐sheets. A large hydrophobic cavity is formed in the interior of Der f 2. Structural comparisons to distantly related proteins suggest a role in lipid binding. Immunoglobulin E (IgE) cross‐reactivity between group 2 house dust mite major allergens can be explained by conserved surface areas representing IgE binding epitopes.

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

BACKGROUND The antibody repertoires of allergic subjects are characterized by the presence of allergen-specific IgE antibodies. We have previously shown that the composition of the IgE repertoire is critical for allergen-mediated activation of human effector cells. Activation of CD4(+) T cells in allergic subjects is highly potentiated by the process of facilitated antigen presentation (FAP), in which allergen in complex with IgE is taken up by B cells through the low-affinity IgE receptor CD23 and presented to T cells. OBJECTIVE We sought to investigate the influence of IgE repertoire complexity on the formation of IgE/allergen/CD23 complexes on B cells and subsequent T-cell activation. METHODS Using defined allergen-specific recombinant IgE and IgG antibodies, we investigated the influence of individual IgE affinity, IgE clonality, specific IgE concentration, and the ratio between IgE specificities on IgE/allergen/CD23 complex formation in vitro. RESULTS Although IgE affinity is an important factor, IgE clonality seems to be governing complex formation, especially with medium- and low-affinity IgE antibodies. We demonstrate that differences in allergen-specific IgE affinity correlate with the efficiency of subsequent T-cell activation. In addition, we show that the complexity of an IgE repertoire also affects the ability of allergen-specific IgG antibodies to block FAP. CONCLUSION The composition of allergen-specific IgE repertoires in individual patients, especially with respect to IgE clonality, might play an important role in the manifestation of allergic disease not only for the immediate allergic reaction through activation of basophils and mast cells but also for the exacerbation of allergic inflammation through recurring activation of allergen-specific T cells by FAP.

Isoallergen Variations Contribute to the Overall Complexity of Effector Cell Degranulation: Effect Mediated through Differentiated IgE Affinity

Most allergens exist in several variants (isoallergens), each of which may be recognized differently by patient IgE. We have previously shown that several properties of the IgE repertoire, including IgE affinity and IgE clonality, are important factors determining degranulation responses of effector cells involved in type I allergic reactions. However, less is known about how the repertoire of naturally occurring isoallergens may affect this response. Thus, in this study, we investigated how individual rIgE Ab clones derived from a human subject are able to distinguish among variants of Der p 2 isoallergens and assessed the impact on basophil degranulation. Biacore analyses showed that individual rIgE clones cloned from an individual allergic to house dust mites recognized Der p 2 with binding affinities varying up to 100-fold between different Der p 2 isoforms. In a well-defined biological system consisting of human basophils sensitized with low rIgE clonality, degranulation responses were directly related to rIgE affinity toward particular rDer p 2 isoallergens. However, basophils sensitized with polyclonal patients’ sera showed no differences in degranulation responses toward the different rDer p 2 isoallergens. In conclusion, our study shows that individual IgE Abs are able to bind single allergens with a broad range of affinities due to natural isoallergen variations, contributing further to the overall complexity of IgE–allergen interactions at the effector cell surface, which is, however, blurred by the polyclonal nature of patients’ IgE repertoires.