Animals and many of their chronic microbial inhabitants form relationships of symbiotic mutualism, which occurs when coexisting life-forms derive mutual benefit from stable associations. While microorganisms receive a secure habitat and constant food source from vertebrate hosts, they are required for optimal immune system development and occupy niches otherwise abused by pathogens. Microbes have also been shown to provide vertebrate hosts with metabolic capabilities that enhance energy and nutrient uptake from the diet. The immune system plays a central role in the establishment and maintenance of host-microbe homeostasis, and B lineage cells play a key role in this regulation. Here, I reviewed the structure and function of the microbiota and the known mechanisms of how nonpathogenic microbes influence B cell biology and immunoglobulin repertoire development early in life. I also discuss what is known about how B lineage cells contribute to the process of shaping the composition of commensal/mutualistic microbe membership.
Keywords: Commensal; Diversification; Gene conversion; Lamina propria; Microbiome; Microbiota; Mucosa; Mutualism; Symbiosis.
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