Lung B Cells Promote Ongoing Allergic Inflammation in a Mouse Model of Asthma via B cell Receptor-Independent Antigen Presentation

The importance of B cells to present antigens for antibody production is well documented. In contrast, very little is known about their capacity to influence T cell response in ongoing allergic inflammation. Using a mouse model of allergic asthma, we observed that lung B cells upregulated expression of MHC‑II, CD86 and OX40L upon house dust mite (HDM) challenge and efficiently presented antigen to T cells in vitro. B cell depletion during challenge severely impaired expansion of activated T cells and their capacity to secrete Th2-type cytokines. Interestingly, efficient HDM presentation was a property not limited to B cells carrying surface Ig specific for HDM, since naïve, memory and B cells of unrelated specificities were equally efficient. Preliminary data suggest the existence of receptor-mediated uptake in the process. Collectively, we highlight the existence of a novel mechanism that may lead to exacerbation of the allergic response.