The incidence of allergic disease has steadily increased over the past decades, affecting one in ten children in Europe today. It is now understood that a lack of neonatal exposure to antigen of harmless microorganisms, which educate the immune system to discriminate between dangerous and harmless insults, is in part responsible for this phenomenon. In the immune system, certain cell subsets are preferentially generated during early life. These include specific B cell subsets, which sustain lifelong. However, surprisingly little is known about the effect of early life antigen exposure on B cell heterogeneity, and the contribution of different B cell subsets in allergic asthma. Given the state of the art, it is fair to say that our understanding of the role of B cells in allergic asthma is limited. This project aims to close the significant gap in our knowledge of the role of B cells in allergic asthma and I will specifically focus on the influence of neonatal exposure to allergens and microbial components on disease development during adult life. This project will combine the use of novel models, state-of-the-art immunology tools and single cell gene expression profiling to address these questions. The knowledge acquired through this project will not only increase our understanding of the roots of allergic asthma in early life, it could also help us to develop targeted preventive measures to alter the natural progression of allergic disease during the course of life.