SELECTED ARTICLES FROM THE RECENT LITERATURE 2007 December 26, 2007 Natural Igm Antibodies Against Pneumococcus Summary Natural antibodies exist in all individuals. However, their molecular and functional characteristics in this "pre-immune repertoire" have not been explored in detail in man. The authors, therefore, looked at seven human IgM monoclonal antibodies selected on the basis of pneumococcal polysaccharide binding and shared molecular and functional characteristics with natural antibodies. These antibodies differed from class-switched antibodies, which are normally serotype-specific. They were polyreactive and bound all pneumococcal polysaccharide capsular serotypes tested. In addition, some bound endogenous antigens including blood group antigens and intermediate filament proteins. All the natural antibodies employed unmutated heavy chain V regions that are formally expressed in the elderly. Of note is that two clones provided passive protection against invasive pneumococcal disease in vivo. Reference Baxendale HE, et al. Natural antibodies to pneumococcus have distinct molecular characteristics and protect against pneumococcal disease. Clin Exp Immunology 2008; 151(1):51-60.   © Copyright 1997-2007 American Academy of Allergy, Asthma and Immunology All rights reserved