Secretory Immunoglobulin A(sIgA) J-Chain Secretory Component 4 heavy chains and 4 light chains (dimeric) J-Chain and secretory component The major immunoglobulin of secretions Not found in serum Secretory Immunoglobulin A (sIgA) ◼ 4 heavy chains and 4 light chains (dimeric) ◼ J-Chain and secretory component ◼ The major immunoglobulin of secretions ◼ Not found in serum Secretory Component J-Chain