CCL8

CCL8, also known as monocyte chemoattractant protein-2 (MCP-2), is a small secreted protein that belongs to the CC chemokine family. CC chemokines are characterized by two adjacent cysteine residues near the amino terminus, which define their receptor-binding properties and role in guiding leukocyte movement. The CCL8 gene is part of the chemokine gene cluster and encodes a precursor protein with a signal peptide that directs secretion.

CCL8 functions as a chemoattractant, promoting the migration of various immune cells to sites of inflammation. It can attract monocytes, memory T cells, natural killer cells, dendritic cells, and, in some contexts, eosinophils. The activity of CCL8 is mediated through interactions with multiple CC chemokine receptors, notably CCR1 and CCR5, among others, leading to cellular chemotaxis and activation.

Expression of CCL8 is inducible and can be upregulated by pro-inflammatory stimuli such as interleukin-1, tumor necrosis factor-alpha, and microbial products. Cells known to produce CCL8 include activated monocytes, macrophages, dendritic cells, endothelial cells, and some epithelial cells, reflecting its role in coordinating immune responses during infection, injury, and inflammatory conditions.

Physiologically, CCL8 participates in leukocyte trafficking, contributing to host defense, tissue repair, and the shaping of the inflammatory milieu. In pathological contexts, altered CCL8 levels have been observed in various inflammatory diseases and certain cancers, where it may influence the composition of the tumor microenvironment by recruiting monocytes and other immune cells.

See also: MCP family; other CCL chemokines; CCR1 and CCR5 receptors.