In vitro protein synthesis by human salivary glands. I. Synthesis of salivary IgA and serum proteins.

Protein synthesis by human salivary glands was studied by incorporation of C-labelled amino acids and autoradiographs of double diffusion tests and immunoelectrophoresis of culture fluids. Submandibular and parotid glands synthesized five serum proteins: one α-globulin, one β-globulin and three immunoglobulins, IgG, IgA and IgM. IgG and IgM, synthesized in small amounts, corresponded immunologically to serum IgG and IgM. IgA, synthesized in large amounts, possessed antigenic determinants supplementary to serum IgA. There was also a synthesis of the free transport piece. Synthesis of serum IgA was never detected, alone or simultaneously with salivary IgA. These facts indicate a transport piece synthesis greater than local salivary IgA synthesis.