The observation that the co-expression of A2, L, and J chains and the SC enhances the production of polymeric SIgA antibodies is inconsistent with previous reports [11, 12] showing that stable transfection of a mouse myeloma cell line (Sp2/0) expressing human SC and mouse-human chimeric dimeric IgA1 produced dimeric but not tetrameric SIgA [12]. Here, IGHA1 is linked to plasma cell myeloma.