T-cell receptor bias in patients with allergic bronchopulmonary aspergillosis

Abstract

CD4+ Th2 helper cell mediated immune responses have been shown to play a crucial role in the pathogenesis of ABPA. HLA and TCR are the candidate genes, which can influence the specificity of these responses. We have previously established a strong association of HLA DR2/5 in ABPA susceptibility. The study was designed to determine whether allergen specific T cell express a limited usage of T cell receptor (TCR) Vβ gene repertoire in ABPA and to find an association of susceptible HLA-DR determinants with the identified TCR gene segments. TCR Vβ typing was performed on antigen specific T cell lines from 14 ABPA and 12 nonABPA patients. The majority of ABPA patients (86%) expressed allergen specific T cells with Vβ13 genes indicating its role in susceptibility, whereas in nonABPA controls, Vβ1 genes T cell repertoires were predominantly expressed. The unrestricted pattern of Vβ gene amplification seen before antigen stimulation suggests an oligoclonal expansion of a specific T cell population in response to the allergen Asp f 1 in ABPA and nonABPA patients. The increased usage of Vβ13 in ABPA and Vβ1 in nonABPA indicates their importance in susceptibility and resistance, respectively.