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M9550164.TXT
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1995-03-04
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Document 0164
DOCN M9550164
TI [Cutaneous immune system]
DT 9505
AU Schmitt D; INSERM Unite 346, Clinique Dermatologique, Hopital;
Edouard-Herriot, Lyon, France.
SO C R Seances Soc Biol Fil. 1994;188(3):207-21. Unique Identifier :
AIDSLINE MED/95136104
AB The skin is not only a physico-mechanical barrier between the
environment and the body, but it also functions as an immune organ. The
immunological function of epidermis is principally linked to the
presence in this tissue of a distinct subpopulation of dendritic cells:
the Langerhans cells (LC). LC constitute 2-4% of epidermal cell
population and within epidermis they are the only cells which express
MHC class II antigens constitutively. LC play a key role in the
initiation of T cell responses to cutaneous antigens by picking up the
antigen and migrating to the draining lymph node where they trigger
specific T cell activation. There is also evidence that keratinocytes
participate in immune responses in the skin since these cells produce a
wide variety of cytokines that can modulate T cell responses. Dendritic
cells comprise a system of highly efficient antigen-presenting cells
which initiate immune responses such as the sensitization of T cells
restricted by major histocompatibility complex molecules, the rejection
of organ transplants and the formation of T-cell-dependent antibodies.
Dendritic cells are found in many non-lymphoid tissues, such as skin and
mucosa (Langerhans cells), and they migrate after antigen capture
through the afferent lymph or the bloodstream to lymphoid organs, where
they efficiently present antigen to T cells. Dendritic cells are
difficult to isolate and, although they originate from bone marrow their
growth and differentiation are still poorly characterized. Granulocyte
macrophage-colony stimulating factor (GM-CSF) favours the out-growth of
dendritic cells from mouse peripheral blood. The cooperation between
GM-CSF and tumour necrosis factor-alpha (TNF-alpha) is crucial for the
generation of human dendritic/Langerhans cells from CD34+ haematopoietic
progenitors. The availability of large numbers of these cells should now
facilitate the understanding of their role in immunological regulation
and disorder. Recent studies reported that after 2-3 days in vitro
incubation, both murine and human LC undergo profound phenotypic
changes, as an enhancement in the expression of MHC class I and II
antigens, LFA-3 and ICAM-1 molecules, a concomitant decrease of CD1a
antigens and a loss of Fc gamma RII. Furthermore, cultured LC (cLC) lose
or markedly reduce their specific cytoplasmic organelles: the Birbeck
granules. Therefore, after a 2-3 days in vitro incubation, LC seem to
acquire most of the features of lymphoid dendritic cells.(ABSTRACT
TRUNCATED AT 400 WORDS)
DE Animal Cytokines/IMMUNOLOGY CD4-Positive T-Lymphocytes/IMMUNOLOGY
CD8-Positive T-Lymphocytes/IMMUNOLOGY Dermatitis, Allergic
Contact/IMMUNOLOGY Dermatitis, Atopic/IMMUNOLOGY English Abstract
Human HLA-D Antigens/IMMUNOLOGY *Immune System In Vitro
Keratinocytes/IMMUNOLOGY Langerhans Cells/IMMUNOLOGY
Skin/CHEMISTRY/CYTOLOGY/*IMMUNOLOGY T-Lymphocyte Subsets/IMMUNOLOGY
JOURNAL ARTICLE REVIEW REVIEW, TUTORIAL
SOURCE: National Library of Medicine. NOTICE: This material may be
protected by Copyright Law (Title 17, U.S.Code).