Beta-chemokine TCA3 binds to mesangial cells and induces adhesion, chemotaxis, and proliferation

Specific receptors for the beta-chemokine TCA3 have been identified on mouse monocyte/macrophage cell lines and on mouse mesangial cells. Using Scatchard plot analysis with 125I-labeled TCA3, a single high-affinity receptor (3-4 nM) was identified. Cells of the monocyte lineage express 1,400 to 8,600 TCA3 binding sites, while mesangial cells display 40,000 to 49,000 sites/cell. Competitive inhibition studies indicated that the TCA3 receptor is unique, although MCP-1, IL-8, and RANTES were weak competitors of TCA3 binding. We also established the functional activity of TCA3 and other chemokines on primary cultures of mouse mesangial cells. TCA3 treatment induces increased mesangial cell adhesiveness to fibronectin. TCA3 is also a chemoattractant for mesangial cells. In addition, TCA3 treatment stimulates [3H]thymidine uptake by mesangial cells. The combined results indicate that TCA3 and other chemokines interact with a broader range of target cells than previously considered.