title: MicroRNA in the adaptive immune system, in sickness and in health.
abstract: BACKGROUND
  MicroRNA are emerging as key regulators of the development and function of adaptive immunity. These 19-24 nucleotide regulatory RNA molecules have essential roles in multiple faucets of adaptive immunity, from regulating the development of the key cellular players to the activation and function in immune responses.
  
  
  CONCLUSIONS
  MicroRNA are involved in T cell and B cell differentiation in the thymus and bone marrow, and subsequent peripheral homeostasis. The contribution of specific microRNA to the adaptive immune response becomes even more apparent during the effector phases: class switching and germinal centre formation in B cells, differentiation into functional lineages in T cells, and activation of antigen-presentation cells through pattern-recognition pathways. With the capacity of microRNA to alter the survival and death of T and B cells, control over microRNA expression is essential to prevent adaptive immune cells from unregulated proliferation. MicroRNA can act both as 'oncomirs' and tumour suppressors, and thus dysregulation of microRNA in lymphocytes can cause malignancies.
  
  
  CONCLUSIONS
  In this review, we will describe the role of microRNA in generating a productive adaptive response, and the consequences if microRNA-mediated repression of lymphocytes is perturbed.
authors.affiliation: VIB and University of Leuven, Leuven, 3000, Belgium. adrian.liston@vib.be
authors.forename: Adrian
authors.initials: A
authors.lastname: Liston
authors.forename: Michelle
authors.initials: M
authors.lastname: Linterman
authors.forename: Li-Fan
authors.initials: LF
authors.lastname: Lu
mesh_terms: D056704:Adaptive Immunity; D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology; D002454:Cell Differentiation / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D015316:Genetic Therapy; D019337:Hematologic Neoplasms / Q000235:genetics* / Q000276:immunology / Q000628:therapy; D006801:Humans; D007107:Immune System / Q000196:embryology / Q000276:immunology*; D035683:MicroRNAs / Q000235:genetics / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D035683:MicroRNAs