Phleum pratense-specific T cells of allergic rhinitis patients display a broader recognition pattern than phleum pratense-specific serum immunoglobulin E

Peptide-induced immune regulation by a promiscuous and immunodominant CD4T-cell epitope of Timothy grass pollen: a role of Cbl-b and Itch in regulation

BACKGROUND

T-cell targeted peptide epitope tolerogens from grass pollen allergens may be useful in treating seasonal allergic rhinitis, but there is urgent need for optimisation of approaches from improved understanding of mechanism.

OBJECTIVE

We sought to identify human leukocyte antigen (HLA)-DR1-restricted epitopes from the Timothy grass pollen allergen, Phleum pratense, and characterise T-cell immune regulation following intranasal administration of a single, immunodominant epitope.

METHODS

T-cell epitopes within P pratense were identified using HLA-DR1 transgenic mice and tetramer-guided epitope mapping (TGEM) in HLA-DR1-positive individuals with grass allergy. An immunodominant epitope was tested in HLA-DR1 transgenics for impact on responses to whole Phl p5 b or peptide. Microarrays and quantitative PCR were used to characterise T-cell immunity.

RESULTS

Peptide 26 (p26) was identified in HLA-DR1 transgenic mice and by TGEM analysis of HLA-DR1-positive individuals with grass allergy. p26 shows promiscuous binding to a wide range of HLA class II alleles, making it of relevance across immunogenetically diverse patients. The epitope is conserved in rye and velvet grass, making it applicable across a spectrum of grass pollen allergy. Intranasal pretreatment of mice with p26 results in significantly reduced T-cell responses. Transcriptomic array analysis in mice showed T-cell regulation in the intranasal treatment group associated with increased expression of members of the Cbl-b and Itch E3 ubiquitin ligase pathway.

CONCLUSIONS

We defined an immunodominant P pratense epitope, p26, with broad binding across multiple HLA class II alleles. Intranasal treatment of mice with p26 results in T-cell regulation to whole allergen, involving the Cbl-b and Itch regulatory pathway.

Anisakis simplex: from obscure infectious worm to inducer of immune hypersensitivity

Infection of humans with the nematode worm parasite Anisakis simplex was first described in the 1960s in association with the consumption of raw or undercooked fish. During the 1990s it was realized that even the ingestion of dead worms in food fish can cause severe hypersensitivity reactions, that these may be more prevalent than infection itself, and that this outcome could be associated with food preparations previously considered safe. Not only may allergic symptoms arise from infection by the parasites ("gastroallergic anisakiasis"), but true anaphylactic reactions can also occur following exposure to allergens from dead worms by food-borne, airborne, or skin contact routes. This review discusses A. simplex pathogenesis in humans, covering immune hypersensitivity reactions both in the context of a living infection and in terms of exposure to its allergens by other routes. Over the last 20 years, several studies have concentrated on A. simplex antigen characterization and innate as well as adaptive immune response to this parasite. Molecular characterization of Anisakis allergens and isolation of their encoding cDNAs is now an active field of research that should provide improved diagnostic tools in addition to tools with which to enhance our understanding of pathogenesis and controversial aspects of A. simplex allergy. We also discuss the potential relevance of parasite products such as allergens, proteinases, and proteinase inhibitors and the activation of basophils, eosinophils, and mast cells in the induction of A. simplex-related immune hypersensitivity states induced by exposure to the parasite, dead or alive.

Novel B and T cell epitopes of chicken ovomucoid (Gal d 1) induce T cell secretion of IL-6, IL-13, and IFN-gamma

BACKGROUND

Chicken ovomucoid (OM, Gal d 1) has an important role in the pathogenesis of IgE-mediated allergic reactions to hen's egg white.

OBJECTIVES

The purpose of this study was to clarify the mechanisms of T cell recognition of ovomucoid using intact OM and chemically modified, characterized and homogeneous solid phase synthetic peptides covering the whole molecule.

METHODS

Eighteen overlapping peptides were prepared by solid phase F-moc polyamide peptide synthesis (SPPS), characterized and high-pressure liquid chromatography (HPLC) purified. The peptides, together with intact, denatured and oxidized OM, were used to stimulate patient-derived cell cultures for mapping T cell epitopes. Proliferation responses, T cell phenotype and cytokine secretion using peripheral blood mononuclear cells (PBMC) from eight individuals and T cell lines (TCL) derived from six hen's egg-allergic patients, were examined. In addition, intact, denatured, oxidized and deglycosylated OM, as well as the peptides solely or with their keyhole limpet haemocyanin (KLH) complexes, were tested. For locating IgE and IgG B cell epitopes, seven egg-allergic patient sera and three OM-polyclonal sera were used. Healthy non-allergic individuals were included as controls.

RESULTS

Seven peptides were recognized by specific IgE, while OM-specific TCL recognized 10 peptides. Six of the OM peptides were commonly recognized both by patient S-IgE and blood-derived TCL. Among those, one novel epitope, peptide OM 61-74, had the ability to bind IgE. Another peptide, OM 101-114, was recognized by IgE and IgG sera, but not by any of the TCLs. In contrast, the peptides OM 41-56, OM 71-84, OM 131-144 and OM 171-186 were exclusively T cell epitopes with no affinity to specific antibodies. Abundant TCL secretion of IFN-gamma, IL-6, IL-4, IL-13, IL-10 and TNF-alpha in response to OM stimulation indicates the contribution of Th2 as well as Th1/Th0 CD4+ cell subsets. For allergic patients moderate amounts of IFN-gamma, IL-13, and high amounts of IL-6, were secreted in response to TCL stimulation by OM peptides. High amounts of IL-6 were secreted in response to all molecular forms of OM (intact-, modified-OM and the peptides 71-84 and 51-64) when TCLs from two non-allergic donors were used.

CONCLUSIONS

One novel B cell epitope (OM 61-74) and 10 T cell epitopes have been identified. The most reactive epitopes of the OM molecule comprise the motifs 1-14 to 71-84, the overlapping peptide-pairs OM 121-134 and OM 131-144 and peptides OM 161-174 and 171-186. Peptides OM 1-14 and 171-186 are the only ones capable of inducing IL-4 secretion. Only one peptide (OM 11-24) induces IL-10 secretion. Those peptides recognized as both T and B cell epitopes or only T cell epitopes, have the potential to induce T cell secretion of moderate to high amounts of IL-13, IFN-gamma and particularly IL-6.