Critical roles of activation-induced cytidine deaminase in the homeostasis of gut flora

S Fagarasan, M Muramatsu, K Suzuki, H Nagaoka… - Science, 2002 - science.org
S Fagarasan, M Muramatsu, K Suzuki, H Nagaoka, H Hiai, T Honjo
Science, 2002science.org
Activation-induced cytidine deaminase (AID) plays an essential role in class switch
recombination (CSR) and somatic hypermutation (SHM) of immunoglobulin genes. We
report here that deficiency in AID results in the development of hyperplasia of isolated
lymphoid follicles (ILFs) associated with a 100-fold expansion of anaerobic flora in the small
intestine. Reduction of bacterial flora by antibiotic treatment of AID−/− mice abolished ILF
hyperplasia as well as the germinal center enlargement seen in secondary lymphoid …
Activation-induced cytidine deaminase (AID) plays an essential role in class switch recombination (CSR) and somatic hypermutation (SHM) of immunoglobulin genes. We report here that deficiency in AID results in the development of hyperplasia of isolated lymphoid follicles (ILFs) associated with a 100-fold expansion of anaerobic flora in the small intestine. Reduction of bacterial flora by antibiotic treatment of AID−/− mice abolished ILF hyperplasia as well as the germinal center enlargement seen in secondary lymphoid tissues. Because an inability to switch to immunoglobulin A on its own does not lead to a similar phenotype, these results suggest that SHM of ILF B cells plays a critical role in regulating intestinal microflora.
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