CCR2 encodes a receptor for MCP1, functioning in inflammatory processes, tumor infiltration and monocyte invasion of artery walls in atherosclerosis. There are two isoforms of CCR2, CCR2A and CCR2B. CCR2 isoforms were expressed by different cell subsets in both normal and IIM muscle. CCR2A was expressed in vessel walls and by some mononuclear cells, especially in cells involved in partial invasion in PM and IBM. CCR2B expression was observed in all satellite cells, in the muscular domain of neuromuscular junctions and in some regenerative fibers of IIM, but not in inflammatory exudates. The sequences of the two isoforms are different from 314-374 aa. This antibody 16154-1-AP is raised against the peptide of 344-360 amino acids of CCR2b. It is specific to CCR2b, not binding CCR2a.