The protective function of secreted IgA has been demonstrated with various model systems, both for the gastrointestinal mucosa as well as for the airways, using passively administered monoclonal IgA (154–157), injected hybridoma cells whose target specific, dimeric IgAs are then transported across the mucosae (“backpack tumor model”) (158–160) and by neutralization of preexisting mucosal IgA immunity with mucosally administered anti-IgA immunoglobulins (80). Here, CD79A is linked to neoplasm.