ICOS mediates the generation and function of CD4+CD25+Foxp3+ regulatory T cells conveying respiratory tolerance

Background: Costimulatory molecules like ICOS are important for the activation and differentiation of T lymphocytes upon allergen contact and thereby strongly affect the decision between the maintaining of tolerance or development of allergic immune response. Methods: Three independent approaches were used to investigate the role of ICOS-mediated costimulation in the development of respiratory tolerance. First, WT mice received anti-ICOSL mAb or control mAb and were tolerized afterwards by intranasal application of OVA. Second, respiratory tolerance was induced in ICOS-deficient and WT mice. Third, tolerized Tre…