Background: Allergen immunotherapy (IT) is a successful treatment associated with decreased Th2 cytokine production by allergen-specific T cells. We have previously demonstrated (Faith et al., J Immunol 1997; 159:53-57) that inhibition of Th2 cytokine production in vitro correlates with impaired tyrosine kinase activity through the TCR. The transcription factor complex, nuclear factor of activated T cells (NF-AT), which regulates Th2 cytokine production is controlled by the activity of tyrosine kinases.
Objective: To address whether decreased Th2 cytokine production by allergen-specific CD4+ T cells following IT is correlated with altered translocation and nuclear expression of the NF-AT family member, NF-AT2, and the activator protein 1 (AP1) component of NF-AT, jun B.
Methods: T cell lines specific for insect venom phospholipase A2 (PLA) were derived from patients prior to and during conventional venom IT. Nuclear expressions of NF-AT and jun B were assessed following stimulation through the TCR. Th1 and Th2 cytokine and IL-10 production by insect venom-specific T cells were also determined. Results were compared with a well-established model system in which anergy was induced in cloned, allergen-specific Th2 cells.
Results: Impaired translocation and decreased expression of NF-AT2 and jun B were detected in PLA-specific T cell lines derived from bee venom-allergic individuals following 16 weeks treatment compared to pre-treatment. These results correlated with significantly reduced production of IL-4 and IL-13 and significantly increased production of IFN-gamma and IL-10 by PLA-specific T cells. Impaired IL-4 and IL-13 production also correlated with defective nuclear expression of NF-AT2/jun B in cloned, anergic allergen-specific Th2 cells.
Conclusion: These results suggested that optimal production of IL-4 and IL-13 by allergen-specific T cells is dependent on the nuclear expression of NF-AT2 and jun B. Thus, specific inhibition of NF-AT2/jun B might be an option in novel and improved forms of allergen IT.