Only Type 2 contains the secretory component, a glycoprotein, which protects IgA from digestion and mediates its active transport across mucosal epithelium. The secretory component is added to salivary IgA by mucosal epithelial cells in the salivary glands, while in the alimentary tract, the secretory component is produced by the enterocytes. | Only Type 2 contains the secretory component, a glycoprotein, which protects IgA from digestion and mediates its active transport across mucosal epithelium. The secretory component is added to salivary IgA by mucosal epithelial cells in the salivary glands, while in the alimentary tract, the secretory component is produced by the enterocytes. |