Basophils arise and mature in bone marrow. When activated, basophils degranulate to release histamine , proteoglycans (. heparin and chondroitin ), and proteolytic enzymes (. elastase and lysophospholipase ). They also secrete lipid mediators like leukotrienes ( LTD-4 ), and several cytokines . Histamine and proteoglycans are pre-stored in the cell's granules while the other secreted substances are newly generated. Each of these substances contributes to inflammation. Recent evidence suggests that basophils are an important source of the cytokine, interleukin-4 , perhaps more important than T cells . Interleukin-4 is considered one of the critical cytokines in the development of allergies and the production of IgE antibody by the immune system. There are other substances that can activate basophils to secrete which suggests that these cells have other roles in inflammation.