Allergic diseases like asthma and hay fever are increasingly common in the Western world, with some 30% of the children allergic to common allergens. Helminths infections also infect up to 30% of the world population. Allergic disorders and helminth infections induce the accumulation of eosinophils in tissues. Eosinophilic inflammation is typically induced by T helper 2 lymphocytes that secrete cytokines to promote eosinophil survival and IgE synthesis by B cells. We have found that these disorders are often accompanied by crystal deposition in the tissues. In this project, we will address the specific role of crystals like uric acid crystals and eosinophil derived Charcot Leyden crystals in the boosting of the Th2 immune response. We will mainly study how crystals influence the function of dendritic cells and innate immune cells. We will address the influence of chemical composition, size of the crystal and will study the molecular mechanism by which crystals have these effects on Th2 immunity. We hope to find novel strategies for intervention in allergic diseases and hope to gain new insights into the mechanism of action of adjuvants.