Effects of interferon‐α on cytokine profile, T cell receptor repertoire and peptide reactivity of human allergen‐specific T cells

A large panel of T cell clones (TCC) specific for the recombinant form of Poa pratensis allergen (rKBG7.2 or Poa p9) were established from the peripheral blood of a grass pollen‐sensitive donor in the absence or presence of recombinant interferon‐α (IFN‐α) in bulk culture and their pattern of cytokine secretion, peptide reactivity and TCR Vβ repertoire was examined. The majority of allergen‐specific TCC derived in absence of IFN‐α produced high amounts of interleukin‐4 (IL‐4) and IL‐5 but not IFN‐γ (Th2 cells), while most of TCC derived in presence of IFN‐α produced IFN‐γ but not, or limited amounts of, IL‐4 and IL‐5 (Th1 or Th0 cells). Of 24 TCC established in the presence of IFN‐α, 22 were able to recognize a single allergen peptide, p26, while none of the clones established in the absence of IFN‐α showed a similar specificity. The majority of both clones expressed the Vβ2 element regardless of whether they were established in the presence of IFN‐α, but the presence of IFN‐α favored the expansion of Vβ2+, Vβ17+ and Vβ22+ Poa p9‐specific T cells, whereas in the absence of IFN‐α, other TCR Vβ‐bearing T cells (Vβ5, Vβ6.7 and Vβ14) were expanded in addition to Vβ2+ T cells. None of Vβ2+ clones established in the absence of IFN‐α reacted with p26, whereas all the Vβ2+ clones established in its presence responded to this peptide. IFN‐α also shifted the TCR Vβ repertoire of both Poa p9‐ and Lolium perenne group 1 (Lol p1)‐specific T cell lines generated from the same patient and from a different grass‐sensitive individual. These data demonstrate that IFN‐α modulates the development of allergen‐specific T cells in vitro, and suggest that IFN‐α may represent an useful tool for novel immunotherapeutic approaches in allergic disorders.