Characterization of T-cell clones specific to ovomucoid from patients with egg-white allergy.

Summary. Background: Allergic reactions to foods are specific problems for infants and young children. Ovomucoid (OM) is one of the major allergens found in egg-white. We previously established several T-cell clones (TCCs) specific to OM in non-polarizing conditions from 4 patients (TM and YN are immediate-type, IH and YT are nonimmediate-type) with egg-white allergy. We characterized their reactive epitopes, antigen-presenting molecules (HLA class II), and usage of TCR alpha and beta genes and the CDR3 loop sequence. Objective: The objective of this study was to characterize these seven clones (TM1.3,TM1.4,YN1.1,YN1.5,IH3.1,IH3.3 and YT6.1) for cytokine production patterns and cell-surface-marker phenotypes. Methods: We measured the production of cytokines, namely interleukin (IL)-4, IL-5 and interferon- γ (IFN-γ) by stimulation with ovomucoid peptides and stained intracellular IL-4 and IFN- γ, and determined cell-surface markers using anti-interleukin-12 receptor (IL-12R) s1, anti-IL-12Rs2 and anti-interleukin-18 receptor α (IL-18Rα ). Results: Most TCCs secreted both IL-4 and IFN-γ in response to the OM peptide mixture, but the secretion patterns were variable; an IFN-γ dominant pattern was seen in IH3.1 and YT6.1, an IFN-γ >IL-4 pattern in TM1.3 and TM1.4, an IL-4> IFN-γ pattern in YN1.5. In intracellular IFN- γ and IL-4 staining, IFN-γ single-positive cells were predominant in TM1.3, TM1.4, IH3.1 and YT6.1 and IFN-γ and IL-4 double-positive cells were predominant in YN1.1, YN1.5 and IH3.3. All TCCs were IL-12Rs1-positive, and TM1.3, IH3.1, IH3.3 and YT6.1 were both IL-12Rs2- and IL-18Rα -positive. TM1.4 and YN1.1 were both IL-12Rs2- and IL-18Rα -negative. Based on these results, TM1.3 and TM1.4, IH3.1 and YT6.1 had a predominantly Th1 character and YN1.1, YN1.5, and IH3.3 possessed a predominantly Th0 character. Conclusions: The phenotypes of TCCs were not in accordance with their clinical manifestations. TCCs established from patients with immediate-type hypersensitivity had either the Th1 or Th0 phenotype as well as those with non-immediate-type hypersensitivity.