Eosinophils as antigen-presenting cells in allergic upper airway disease

Purpose of review The recognition of eosinophils as complex immunomodulatory cells has been increasing in recent years. One prominent novel immunomodulatory function of eosinophils is their role as antigen-presenting cells (APCs). This review will examine the evidence that has enhanced the understanding of eosinophils as APCs in the context of allergic inflammation, with a focus on data applicable to allergic upper airway disease. Recent findings Recent studies expand on prior findings that eosinophils can express major histocompatibility complex class II and costimulatory molecules. Eosinophils have also been found to traffic to regional lymph nodes and act as professional APCs in various experimental settings. Summary Accumulating evidence of the ability of eosinophils to act as APCs suggests that eosinophils may have more complex immunomodulatory roles in allergic upper airway disease than previously appreciated.