Important note: Information in this article was accurate in 1998. The state of the art may have changed since the publication date.
In vivo microbial stimulation induces rapid CD40 ligand-independent production of interleukin 12 by dendritic cells and their redistribution to T cell areas [see comments]
J Exp Med. 1997 Dec 1;186(11):1819-29. Unique Identifier : AIDSLINE MED/98044247 Sousa CR; Hieny S; Scharton-Kersten T; Jankovic D; Charest H; Germain RN; Sher A; Lymphocyte Biology Section, Laboratory of Immunology, National; Institute of Allergy and Infectious Diseases, National Institutes of; Health, Bethesda, Maryland 20892-1892, USA. caetano@nih.gov
Abstract:
The early induction of interleukin (IL)-12 is a critical event in determining the development of both innate resistance and adaptive immunity to many intracellular pathogens. Previous in vitro studies have suggested that the macrophage (MPhi) is a major source of the initial IL-12 produced upon microbial stimulation and that this response promotes the differentiation of protective T helper cell 1 (Th1) CD4+ lymphocytes from precursors that are primed on antigen-bearing dendritic cells DC). Here, we demonstrate by immunolocalization experiments and flow cytometric analysis that, contrary to expectation, DC and not MPhi are the initial cells to synthesize IL-12 in the spleens of mice exposed in vivo to an extract of Toxoplasma gondii or to lipopolysaccharide, two well characterized microbial stimulants of the cytokine. Importantly, this production of IL-12 occurs very rapidly and is independent of interferon gamma priming or of signals from T cells, such as CD40 ligand. IL-12 production by splenic DC is accompanied by an increase in number of DCs, as well as a redistribution to the T cell areas and the acquisition of markers characteristic of interdigitating dendritic cells. The capacity of splenic DC but not MPhi to synthesize de novo high levels of IL-12 within hours of exposure to microbial products in vivo, as well as the ability of the same stimuli to induce migration of DC to the T cell areas, argues that DC function simultaneously as both antigen-presenting cells and IL-12 producing accessory cells in the initiation of cell-mediated immunity to intracellular pathogens. This model avoids the need to invoke a three-cell interaction for Th1 differentiation and points to the DC as both a sentinel for innate recognition and the dictator of class selection in the subsequent adaptive response.
Keywords: *Dendritic Cells/SECRETION *Interleukin-12/SECRETION Comment in: J Exp Med 1997 Dec 1;186(11):1799-802
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Important note: Information in this article was accurate in 1998. The state of the art may have changed since the publication date.
