Cytokines are immunomodulatory and inflammatory compounds produced by many different cell types. The IL-1 family consists of at least eleven cytokines including IL-18 and IL-13 and are essential to the host defence against severe infections and mediate inflammation. IL-18 also enhances tumour rejection and has high capacity to augment the cytotoxicity of NK cells and T cells. IL-33 stimulates basophils and mast cells to produce cytokines and histamine independently of IgE. Mast cells play a crucial role in the development of allergy through the cross-linking of their surface receptors for IgE leading to degranulation and inflammation. Activated mast cells induce the generation of PGD2, detectable in 2-15 minutes after challenge, and LTC4. Here we review the interrelationship between PGD2, IL-1 family members and mast cells.