Monocyte Chemoattractant Protein 4 (MCP-4), also called CCL13, is induced by inflammatory proteins such as IL-1 and TNFα. MCP-4 is a ligand for three different G protein coupled receptors, CCR2, CCR3 and CCR5. MCP-4 activates signaling in monocytes, T lymphocytes, eosinophils and basophils and this signaling is associated with the allergic response. Recombinant human MCP-4 is a non-glycosylated protein, containing 74 amino acids and having a molecular mass of 8.5 kDa.

Monocyte chemotactic protein-4 (MCP-4; CCL-13) is a biomarker of asthma. Airway expression of monocyte chemotactic protein-4 is known to be increased in asthmatic airways where it is induced by proallergic cytokines, but the relationship of its systemic expression to asthma and naturally occurring exacerbations is unknown. The MCP-4 levels are higher in individuals with an acute asthma exacerbation than in subjects with chronic-stable asthma (513 vs. 355 pg/mL) (p = 0.002). The MCP-4 is a systemically expressed biomarker that independently predicts susceptibility to asthma and is directly associated with exacerbations. Elevated MCP-4 levels identify a group of asthmatics with systemic evidence of allergic inflammation who may be at risk for exacerbations or may benefit from abrogation of MCP-4.