Recombinant Human IgA Expressed in Insect Cells

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 91; no. 18; pp. 8348 - 8352
• Main Authors: Carayannopoulos, Leonidas, Max, Edward E., Capra, J. Donald
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 30.08.1994; National Acad Sciences; National Academy of Sciences
• Subjects: Animals; Antibodies; Baculoviridae - genetics; Biochemistry; Complement C3 - metabolism; Erythrocytes; Experimentation; Genes; Genes, Immunoglobulin; Genetic Vectors; Glycosylation; Humans; Immunity (Disease); Immunoglobulin A - genetics; Immunoglobulin A - metabolism; Immunoglobulin alpha-Chains - genetics; Immunoglobulin J-Chains - genetics; Immunoglobulin kappa-Chains - genetics; Immunology; Insect viruses; Insecta; Insects; Mice; Molecules; Moths; Oligosaccharides; Protein Processing, Post-Translational; Proteins; Receptors; Receptors, Fc - metabolism; Recombinant Fusion Proteins - immunology; Recombinant Fusion Proteins - metabolism; Viruses
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.91.18.8348

IgA serves as the first line of humoral defense at all mucosal surfaces and is present in large quantities in serum. To map the sites of interaction of immune effector molecules with the IgA constant region (Cα), we have expressed soluble, chimeric human IgA in insect cells using recombinant baculoviruses. This antibody is correctly assembled into heavy chain/light chain heterodimers, N-glycosylated, and secreted by the insect cells; further, when coexpressed with a human J chain, the antibodies can assemble into dimers. The recombinant protein is authentic by a number of criteria, including antigen-binding, recognition by monoclonal antibodies, complement fixation via the alternative pathway, and specific binding to the monocyte IgA Fc receptor. We have also constructed viruses which encode structurally altered IgA heavy chains. Using one of these variant viruses, we have shown that glycosylation of the second domain of Cαis required for interaction with the monocyte IgA Fc receptor. This system should prove useful in further characterization of the structure-function relationships in human Cα.