Control of early viral and bacterial distribution and disease by natural antibodies

Natural antibodies are often dismissed from immunological analysis as "back ground," but they may play an important role in conferring immunity against infections. In antibody-free mice infected with various viruses or with Li steria monocytogenes, viral or bacterial titers in peripheral organs, inclu ding the kidney and brain, were 10 to 100 times greater than in antibody-co mpetent mice (and enhanced their susceptibility to some infections), and ti ters in secondary Lymphoid organs were 10 to 100 times lower than in antibo dy-competent mice. Thus, natural antibodies play a crucial role by preventi ng pathogen dissemination to vital organs and by improving immunogenicity t hrough enhanced antigen-trapping in secondary Lymphoid organs.