51098 IMG 85 (3)

Polymeric and secretory immunoglobulin A

B.PolylgAconsistsof twomlgAmolecules linkedend toend withJ Chain bondńig to both mlgA subunits via cysteinę (Cys) 471 of one a-chainfromeack monomer

C

1.    Secretory component (SC) binds only to polymeric IgA or IgM

2.    SC binding by plgA and IgM is dependent on tbe presence of J chain