Background: MicroRNAs (miRNAs) are short singlestranded RNA molecules that regulate gene expression post-transcriptionally. Several hundred miRNAs exist in the mammalian genome and regulate developmental processes, cell cycle, and survival.
Methods: In this review,we highlight generalmodes of miRNA function and relate them to how such regulation can be beneficial for immune homeostasis and the prevention of autoimmune diseases.We highlight examples of experimentally verified miRNA function and their target genes in the immune system and place them in context of concepts relevant to an understanding of autoimmune pathogenesis. Where available, we refer to clinical correlations. Finally, we speculate how emerging knowledge about miRNA function in the immune system might be used diagnostically and therapeutically.