Thursday 01 March 2007
CEA
Effector T-lymphocytes acts as suppressors following immunosuppressive HLA-G1 acquisition
Blood (2007) 109 :2040-2048
CEA
The Saint-Louis Hospital Blood Immunology Research Department (I²BM/SRHI, CEA Fontenay-aux-Roses) has demonstrated that the HLA-G immunosuppressive molecule can be rapidly exchanged between antigen-presenting cells and effector T-lymphocytes during cell-cell interactions.
Suppressor lymphocytes are cells involved in immunity whose function is to prevent or block immune responses. Suppressor cells are considered the opposite of effector cells. Effector T-lymphocytes that achieve a rapid (i.e. within minutes) but transitory (lasting a few hours) acquisition of the HLA-G molecule immediately change their effector function into a suppressor function, which in other words means they switch from attacker to protector. These results demonstrate the existence of a new type of suppressor T-lymphocyte that can perform this function via captured exogenous molecules without changing their own, specific function.
The functional impact of the transfer of the HLA-G molecule has made it possible to demonstrate the existence of a new mechanism of immune suppression. This mechanism is potentially involved in tumour survival as well as in protecting the foetus against the mother’s immune system. This research was published as an editorial in the same journal (Wiendl H. 2007. Blood) as well as in Nature Reviews in Immunology (Davis D. 2007. Nat Rev Immunol).
Références :
LeMaoult J., Caumartin J, Daouya M, Favier B, Le Rond S, Gonzalez A, Carosella ED. 2007. Immune regulation by pretenders : cell-to-cell transfers of HLA-G make effector t cells act as regulatory cells. Blood 109:2040-2048.
Caumartin J, Favier B, Daouya M, Guillard C, Moreau P, Carosella ED, LeMaoult J. 2007. Trogocytosis-based generation of suppressive NK cells. The EMBO Journal 26, 1423–1433
Co-incubation time (in minutes)
Transfer of portions of HLA-G-containing membranes from an antigen-presenting cell to a T-lymphocyte. APC-HLA-G1: antigen-presenting cell expressing HLA-G1. The cell itself is labelled in red, while HLA-G1 is labelled in green. T-cell: T-lymphocyte, labelled in blue. (A): The area of contact between the antigen-presenting cell (APC) expressing HLA-G and the effector T-lymphocyte becomes clearly visible after just 5 minutes of co-incubation. (B): The transfer of the HLA-G molecule can be seen after 15 minutes of co-incubation. HLA-G-loaded membrane fragments are visible outside the zone of contact between the APC and the T-lymphocyte.