Chemotactic factor that attracts monocytes, lymphocytes, basophils and eosinophils, but not neutrophils. Signals through CCR2B and CCR3 receptors. Plays a role in the accumulation of leukocytes at both sides of allergic and non-allergic inflammation. May be involved in the recruitment of monocytes into the arterial wall during the disease process of atherosclerosis. May play a role in the monocyte attraction in tissues chronically exposed to exogenous pathogens. Widely expressed. Found in small intestine, thymus, colon, lung, trachea, stomach and lymph node. Low levels seen in the pulmonary artery smooth muscle cells. By IL1/interleukin-1 and TNF. One major form (form long), and two minor forms (short chain and medium chain) are produced by differential signal peptide cleavage. The medium chain is about 30-fold less active than the long chain. This protein can bind heparin. Belongs to the intercrine beta (chemokine CC) family. CCL13 entry