Molecular and functional analysis of the antigen receptor of Art v 1-specific helper T lymphocytes

Ninety-five percent of patients with mugwort allergy are sensitized to Art v 1, the sole major allergen in mugwort (Artemisia vulgaris) pollen. Sixty-nine percent of patients recognizing the single immunodominant T-cell epitope Art v 1(25-36) have an HLA-DRB1*01 phenotype.

We studied cloning and functional expression of a human alphabeta T-cell receptor (TCR) specific for Art v 1(25-36).

TCR chains were RT-PCR amplified from an Art v 1(25-36)-specific T-cell clone, retrovirally transferred, and functionally tested in Jurkat T cells or alternatively in peripheral blood T lymphocytes of nonallergic individuals.

The alpha-chain of the TCR is composed of TRAV17 and TRAJ45 segments, and the beta-chain uses TRBV18, TRBD1, and TRBJ2-7. Analyses of 23 other Art v 1-specific T-cell clones did not reveal preferential usage of the TRAV17, TRBV18, or other TCR gene families. Efficient TCR transfer into Jurkat T cells was shown by binding of TCR Vbeta18-specific mAb and DRB1*0101/Art v 1 tetramers. Transgenic Jurkat T cells specifically recognized syngeneic EBV B cells pulsed with Art v 1(25-36) peptide and artificial antigen-presenting cells expressing invariant chain::Art v 1 fusion proteins. Moreover, transfer of the TCR into peripheral blood lymphocytes generated T cells that were Art v 1 reactive. Activation of transgenic T cells by artificial antigen-presenting cells was strictly dependent on costimulation.

For the first time, a detailed molecular and functional analysis of a human allergen-specific TCR is presented.