Increased inhibitory surface marker PD-1 expression in Th2+T cells in allergen-specific immunotherapy

Recent evidence has shown that T cell exhaustion is implicated in Allergen-specific Immunotherapy (AIT). However, how T cell exhaustion plays a role in AIT is far from clear. Our study aimed to investigate T cell exhaustion associated with allergen exposure during AIT in mice. Ovalbumin (OVA) -sensitized C57BL/6J asthma mouse and AIT mouse models were constructed. Quantitative real-time PCR (qRTPCR) and flow cytometry were used to monitor the occurrence of local and systemic Th2+T cells exhaustion in OVA-sensitized mice. The inhibitory surface marker programmed cell death protein 1 (PD-1) on Th2+T cells was significantly upregulated in AIT mice compared with asthmatic and control mice. The inhibitory surface marker cytotoxic T lymphocyte-associated protein 4 (CTLA-4) on Th2+T cells showed no significant difference between the AIT, asthma and control mice. Collectively, our study indicated that the expression of PD-1 on Th2+T cells was increased in AIT. T cell exhaustion plays an important role in AIT.