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The tolerogenic molecule CD95‐L is expressed on the plasma membrane of human activated, but not resting, Langerhans' cells.
Author(s) -
De Panfilis G.,
Venturini M.,
Lavazza A.,
Mommaas M. A.,
Semenza D.,
Torresani C.,
Pasolini G.
Publication year - 2003
Publication title -
experimental dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.108
H-Index - 96
eISSN - 1600-0625
pISSN - 0906-6705
DOI - 10.1034/j.1600-0625.2003.00079.x
Subject(s) - fas receptor , microbiology and biotechnology , epidermis (zoology) , chemistry , membrane , antigen , biophysics , apoptosis , biology , immunology , biochemistry , programmed cell death , anatomy
Although dendritic cells (DC) are well known for their immunogenic capacities, they may even induce peripheral T‐cell tolerance, and such a tolerogenic potential can be exerted in mouse through the expression on the DC plasma membrane of the CD95‐ligand (CD95‐L) molecule, which is able to trigger apoptosis of CD95‐expressing antigen‐specific T cells. We therefore asked whether epidermal DC, namely Langerhans' cells (LC), either resting (i.e. within the epidermis, ‘ in situ ’) or activated (i.e. suspended from the epidermis) or both, could express the CD95‐L molecule on the plasma membrane. For such a purpose, two colloidal gold‐immunoelectron microscopy (IEM) double‐step procedures were carried out: an ‘ in situ ’ method, able to investigate resting LC, was performed on ultrathin frozen sections obtained by ultracryomicrotomy (UCMT) of normal skin biopsies; a pre‐embedding (P‐E) method, able to investigate suspended LC, was performed on epidermal cells (EC) suspended from normal skin specimens. In UCMT/IEM sections, resting LC showed gold particles within the cytoplasm but very rarely within organelles and never along the plasma membrane: resting LC are therefore capable of synthesizing CD95‐L but not of expressing it in a functional location, thus autoreactive phenomena against CD95‐expressing EC being avoided in normal epidermis. On the other hand, in P‐E/IEM preparations, suspended LC showed several gold particles along the plasma membrane: activated LC are therefore capable of expressing CD95‐L in a functional location, thus bearing the potential to exert tolerogenic capabilities against CD95‐expressing T cells, e.g. to prevent inflammatory/autoimmune cutaneous disorders and/or favor the resolution thereof.