Lege Artis Medicinae

[HUMAN DENDRITIC CELLS AND INFECTIVE AGENTS]

KIS Zoltán

APRIL 21, 2004

Lege Artis Medicinae - 2004;14(04)

[Dendritic cells represent important components of the innate and adaptive immune responses. Human dendritic cells can be divided into two major subsets: myeloid and plasmacytoid (lymphoid) dendritic cells. The unique function of the dendritic cells is to capture antigens, present and to activate the antigenic peptides to the T lymphocytes. Dendritic cells go through a maturation process both in vitro and in vivo. By the use of pathogenrecognition- receptors the immature dendritic cells sense diverse pathogens or their various components, or cellular factors produced by the infected neighboring non-dendritic cells, and maturation signals are transduced for the dendritic cells. The heterogeneity of the pathogen-recognition-receptors and the microbial stimuli initiate a broad range of interactions between dendritic cells and infectious agents. Dendritic cells infected with certain viruses produce only a few infectious particles, but express and present viral antigens to T lymphocytes and immune response is initiated (influenza virus). Dendritic cells infected with certain pathogens not only initiate immune response but also disseminate the pathogen (human immunodeficiency virus, Mycobacterium tuberculosis). Some pathogens are killed in the dendritic cells, but the antigens are presented to the T cells, and immune responses are induced (Chlamydia trachomatis and Chlamydia psittaci). Dendritic cells capture antigens produced by infected neighbouring cells and present them to T lymphocytes, thus immune response is initiated (human cyto-megalovirus, herpes simplex virus). Dendritic cells are responsible for virus-induced immunosupp-ression; dendritic cells infected with certain pathogens form syncytia with T cells, thereby contribute to the suppression of T cell functions directed against opportunistic infections (measles virus). Dendritic cells can present not only foreign antigens but also self-antigens and when immature dendritic cells become mature upon exposure to inflammatory processes or to pathogens capable of activating them they can induce autoimmunity.]

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