Zulehner N, Nagl B, Briza P, Roulias A, Ballmer-Weber B, Zlabinger GJ, Ferreira F, Bohle B. Characterization of the T-cell response to Dau c 1, the Bet v 1-homolog in carrot.
Allergy 2017;
72:244-251. [PMID:
27222434 PMCID:
PMC5244680 DOI:
10.1111/all.12938]
[Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/22/2016] [Indexed: 12/02/2022]
Abstract
Background
In contrast to other Bet v 1‐related food allergens, the major carrot allergen, Dau c 1, has been suggested to induce food allergy independently from Bet v 1. As T cells are crucial in the sensitization process, we sought to characterize the T‐cell response to Dau c 1 and its cross‐reactivity with Bet v 1.
Methods
Dau c 1‐specific T‐cell lines (TCL) and clones (TCC) established from PBMC of birch pollen‐allergic patients with carrot allergy were analyzed for reactivity to Bet v 1, epitope specificity, allergen‐induced cytokine secretion, and expression of integrins α4β7 and α4β1, critical for gut and lung homing, respectively. mRNA expression of GATA3 and Tbet was analyzed in sorted CD3+CD4+CFSElow cells proliferating upon stimulation of PBMC with Dau c 1 or Bet v 1. Dau c 1 was incubated with endolysosomal proteases, and the resulting fragments were identified by mass spectrometry.
Results
Among 14 distinct T‐cell‐activating regions, Dau c 1139–153 was recognized by 55% of the patients. Only 6 of 15 (40%) Dau c 1‐specific TCL and 9 of 21 (43%) TCC reacted with Bet v 1. Bet v 1‐nonreactive TCC were mainly Th1‐like and showed a higher expression of the integrin β7 and a significantly lower expression of the integrin β1 than Bet v 1‐positive TCC. A Th1‐like response was also detected in Dau c 1‐reactive CD3+CD4+CFSElow cells. Full‐length Dau c 1 was still detectable after 48 h of endolysosomal degradation. Proteolytic fragments of Dau c 1 matched its T‐cell‐activating regions.
Conclusion
Dau c 1 displays several characteristics of sensitizing allergens, namely a major T‐cell‐activating region, low susceptibility to endolysosomal degradation, and induction of a Bet v 1‐independent T‐cell response. These cellular insights confirm that the major carrot allergen has a special status among Bet v 1‐related food allergens.
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