Role of the Neonatal Fc Receptor for IgG in the Pathophysiology of Lupus
Role of the Neonatal Fc Receptor for IgG in the Pathophysiology of Lupus
This study evaluates the expression of the neonatal fc receptor (FcRn) in white blood cells
 and antigen-presenting cells (APC) in active lupus patients compared to inactive lupus
 patients and control to investigate if it's upregulated or not.
FcRn is an intracellular receptor which binds the Fc of immunoglobulins G (IgG) and albumin
 which induce an upgraded half-life of this two proteins.

 It's extended role involve the regulation of immune complexes and anti-tumoral immunity, some
 studies showing a direct correlation between it's expression and the tumor surface and
 prognosis.

 Recently a role in the upregulation of humoral response with a increase of the antibodies's
 diversity and a more efficient priming of lymphocyte B have been evocated.

 The lupus erythematosus is an auto-immune disease mediated by IgG and immune complexes
 characterized by a high diversity of autoantibodies and a large dysregulation of the immune
 system in all it's components.

 In this study, by analogy with the founding in anti-tumoral immunity, the investigators
 hypothesised that in an active lupus disease the expression of FcRn is upregulated in the
 white blood cells and in APC.

 This is followed by an extended half life of IgG autoantibodies and immune complexes inducing
 direct damages by their deposit in tissues and indirectly by upregulating the humoral
 response, leading to anormal production of a large panel of autoantibodies.
Inclusion criteria:

 -  Lupus erythematosus newly diagnosed or active

 -  Inactive lupus erythematosus

 -  Needing a blood sample for diagnosis or follow up

 -  Signed informed consent

 Exclusion criteria:

 -  Other auto immune disease

 -  Pregnant or brest feeding

 -  Legal protection or protected adults