Background PAR-2, a G-coupled receptor activated by serine proteinases, is widely expressed in the human body and is involved in inflammation. We have shown that PAR-2 activation in the airways plays a pathogenetic role in mouse models of asthma. PAR-2 expression is increased in the epithelium of asthmatic subjects, but its expression on immune and inflammatory cells of asthmatic individuals has not been. Severe asthma has different phenotypic characteristics from mild-moderate disease. In this study we compared PAR-2 expression on immune cells between subjects with mild/moderate and severe asthma.