Calcium dependence of A-CAM function in human renal epithelium

Previously we have used immunocytochemistry to identify A‐CAM as a major cell adhesion molecule in human renal tubular epithelium. In this study, we demonstrate the calcium dependence of cell‐cell adhesion and A‐CAM function in cultured human renal epithelial cells. Separation of adjacent cells was seen within 1 min following sequestration of calcium from the culture medium with EDTA. This loss of intercellular adhesion in low calcium conditions was accompanied by the disappearance of A‐CAM immunoreactivity. The changes were reversible and on return to normal calcium concentrations, A‐CAM immunoreactivity reappeared and cell adhesion was re‐established. The time course of this recovery was slow, taking 2–3 h. These results demonstrate the calcium dependence of cell adhesion in cultured human renal epithelial cells and confirm the adhesive function of the immunoreactive A‐CAM molecule.