Dendritic Cells as Sensors of Infection

• Published in: Immunity 2001-05, Vol.14 (5), p.495-498
• Main Author: e Sousa, Caetano Reis
• Format: Article
• Language: English
• Subjects: Animals; Dendritic Cells - immunology; Drosophila; Humans; Infection - etiology; Infection - immunology
• ISSN: 1074-7613; 1097-4180
• DOI: 10.1016/S1074-7613(01)00136-4

A stable environment and an abundant supply of nutrients make an inviting place for a pathogen. Consequently, complex multicellular organisms have had to evolve defense mechanisms to make their internal environment more hostile to invaders. All immune systems have one feature in common: they respond to infection by switching from a resting to an active state. For example, Drosophila flies do not make microbicidal peptides until infected by fungi or bacteria. Similarly, T and B cells are generally resting in the absence of infection although they can be rapidly activated in response to an invading pathogen. Thus, there must be key features of an infectious process that trigger immune responses. These features are recognized primarily by cells and molecules of the innate immune system. The innate response limits infection and activates antigen-presenting cells (APC) to trigger adaptive immunity, which increases specificity and generates memory. Over the last 25 years, dendritic cells (DC) have emerged as the major APC involved in this process. DC provide T cells with antigens as complexes with MHC or MHC-like molecules and, simultaneously, deliver critical information about the context in which the antigens were encountered. An infectious context promotes DC immunogenicity and the development of immunity while absence of infection fails to do so. DC also convey information about the nature of the infectious agent, favoring the appropriate class of T cell response. This review explores the topic of DC as sensors of infection and its consequences for the adaptive response.