Polymeric IgA binds to the polymeric immunoglobulin receptor on the basolateral surface of epithelial cells and is taken up into the cell via transcytosis.
In the context of epithelial cells, polymeric immunoglobulin A (IgA) binds to its specific receptor on the outer surface of these cells, triggering a cellular response that ultimately leads to its internalization through a specialized transport mechanism called transcytosis.