The T Cell Response to Art v 1, the Major Mugwort Pollen Allergen, Is Dominated by One Epitope

Abstract

Mugwort (Artemisia vulgaris) pollen allergens represent the main cause of pollinosis in late summer in Europe. At least 95% of sera from mugwort pollen-allergic patients contain IgE against a highly glycosylated 24- to 28-kDa glycoprotein. Recently, this major allergen, termed Art v 1, was characterized, cloned in Escherichia coli, and produced in recombinant form. In the present study we characterized and compared the T cell responses to natural (nArt v 1) and recombinant Art v 1 (rArt v 1). In vitro T cell responses to nArt v 1 and rArt v 1 were studied in PBMC, T cell lines (TCL), and T cell clones (TCC) established from PBMC of mugwort-allergic patients. Stimulation of PBMC or allergen-specific TCL with either nArt v 1 or rArt v 1 resulted in comparable proliferative T cell responses. Eighty-five percent of the TCC reactive with rArt v 1 cross-reacted with the natural protein. The majority of the CD4+CD8−TCR αβ+ Art v 1-specific TCC, obtained from 10 different donors, belonged to the Th2 phenotype. Epitope mapping of TCL and TCC using overlapping peptides revealed a single immunodominant T cell epitope recognized by 81% of the patients. Inhibition experiments demonstrated that the presentation of this peptide is restricted by HLA-DR molecules. In conclusion, the T cell response to Art v 1 is characterized by one strong immunodominant epitope and evidently differs from the T cell responses to other common pollen allergens known to contain multiple T cell epitopes. Therefore, mugwort allergy may be an ideal candidate for a peptide-based immunotherapy approach.

Spontaneous CD4+ T Cell Responses against TRAG-3 in Patients with Melanoma and Breast Cancers

“…Another study in humans has reported the existence of Th2-type CD4 ϩ T cells directed against a single immunodominant epitope from mugwort pollen in allergic patients, which coexisted with Ag-specific IgE Abs and exhibited a large TCR repertoire (52). These observations led us to examine the TCR repertoire of the TRAG-3-specific CD4 ϩ T cells derived from PBL of either a melanoma patient with TRAG-3-expressing tumor or a normal donor.…”

Humoral and Cellular Cross-Reactivity between Amb a 1, the Major Ragweed Pollen Allergen, and Its Mugwort Homolog Art v 6

“…Binding of serum IgE to ragweed and mugwort pollen extracts was tested in immunoblots as described previously (20). Allergen-specific ELISAs were performed as described previously (21) using nAmb a 1 and nArt v 6, respectively.…”

“…PBMCs (2 3 10 5 ) were stimulated in triplicates with concentrations from 0.3 to 20 mg/ml rAmb a 1 or rArt v 6. Allergen-specific TCL were established as described previously (20). In brief, 1.5 3 10 6 PBMCs were initially stimulated either with ragweed or mugwort pollen extract (10 mg/ml), Amb a 1 (2.5 mg/ml), or Art v 6 (2.5 mg/ml).…”

“…In brief, 1.5 3 10 6 PBMCs were initially stimulated either with ragweed or mugwort pollen extract (10 mg/ml), Amb a 1 (2.5 mg/ml), or Art v 6 (2.5 mg/ml). TCC were established from TCL by limiting dilution as described previously (20), and most of them have been described elsewhere (22). The proliferative responses of TCL or TCC to Amb a 1 (2.5 mg/ml) or Art v 6 (2.5 mg/ml) or allergen-derived synthetic peptides (5 mg/ml) were measured after 48 h. Allergen concentrations used for in vitro stimulations had initially been optimized in titration experiments (data not shown).…”

“…Cutoff was defined as mean OD + 5 SD of values obtained with sera from five nonallergic individuals. OD ratios of Amb a 1/Art v 6 within 0.5 and 2.0 were interpreted as "comparable" IgE reactivity (patients 23-44); OD ratios $2 or #0.5 were interpreted as "preferential" recognition of Amb a 1 (patients [19][20][21][22] 3 for mugwort, respectively. All patients had recurrent rhinitis/conjunctivitis during late summer and positive skin prick tests to either ragweed or mugwort pollen or to both weeds.…”