Ecto-5'-nucleotidase (CD73): an emerging role as prognostic factor in allergic sensitization.

Over the years, the importance of the epithelium in the assessment of allergic sensitization and development of allergic diseases has increased. Sensitization to allergens appears to be influenced by genetic and external environmental factors. However, not all subjects exposed to environmental factors that damage epithelial cells suffer from allergic diseases. On this basis, identifying the signaling pathways that characterize the different phenotypes and endotypes of allergy is of high priority for a successful personalized therapy. Ecto-5'-nucleotidase/CD73 is a membrane-bound enzyme responsible for extracellular adenosine accumulation from AMP derived, in turn, from the hydrolysis of extracellular ATP. Current knowledge suggests that CD73 expression and enzymatic activity at epithelial barriers would be of fundamental importance to control the first defense against allergens, by preserving both physical and immunological epithelial barrier functions. Here, we highlight evidence for a crucial role of CD73 in features of allergic sensitization and the potential of this enzyme as prognostic marker and target of therapeutic intervention.