Targeting mucosal sites by polymeric immunoglobulin receptor-directed peptides.

Polymeric immunoglobulins provide first line humoral defense at mucosal surfaces to which they are specifically transported by the polymeric immunoglobulin receptor (pIgR) on mucosal and glandular epithelial cells. Previous studies from our laboratory suggested that amino acids 402-410 of the Calpha3 domain of dimeric IgA (dIgA) represented a potential binding site for the pIgR. Here by binding human secretory component to overlapping decapeptides of Calpha3, we confirm these residues and also uncover an additional site.