Secretory component of epithelial cells is a surface receptor for polymeric immunoglobulins.
Epithelial cells of human fetal intestines and of a colonic carcinoma cell line (HT-29) exhibited intracellular and surface binding of polymeric immunoglobulins of IgA and IgM classes; monomeric IgA and IgG did not bind to these cells. Secretory component was identified as the receptor involved in the immunoglobulin binding. This conclusion was confirmed by the following experiments: trypsin abrogated the surface binding of polymeric immunoglobulin, reappearance of surface secretory component (SC) restored immunoglobulin binding; the appearance of SC in developing fetal tissues coincided with their potential to bind polymeric immunoglobulin; anti-SC reagents inhibited the binding of immunoglobulins to epithelial cells; and SC-containing secretory IgA did not bind to the surface of HT-29 cells.
D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D003110:Colonic Neoplasms / Q000378:metabolism; D004848:Epithelium / Q000378:metabolism*; D006801:Humans; D007070:Immunoglobulin A / Q000378:metabolism; D007128:Immunoglobulin Fragments / Q000378:metabolism*; D007075:Immunoglobulin M / Q000378:metabolism; D007136:Immunoglobulins / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000378:metabolism; D011955:Receptors, Drug; D012635:Secretory Component / Q000378:metabolism*; D014357:Trypsin / Q000494:pharmacology
D007070:Immunoglobulin A; D007128:Immunoglobulin Fragments; D007075:Immunoglobulin M; D007136:Immunoglobulins; D011955:Receptors, Drug; D012635:Secretory Component; D014357:Trypsin