Plants offer a cost-effective bioreactor to produce antibodies of diverse types. Recent studies demonstrate that secretory IgA, the predominant antibody isotype of the mucosal immune system, can be made in large quantities in plants. CaroRx, the lead SIgA antibody being developed by Planet Biotechnology Inc., has demonstrated activity in pilot phase II trials versus S. mutans, the major pathogen contributing to development of dental caries. Numerous other SIgA plantibodies are in preclinical development.