Neonatal Fc receptor expression in lymphoid and myeloid cells in
systemic lupus erythematosus
The neonatal Fc receptor (FcRn) is an ubiquitously-expressed protein
historically involved in IgG and albumin recycling. Recent data suggest
an involvement in the pathophysiology of antibody-mediated autoimmune
diseases. Among them, systemic lupus erythematosus (SLE) implies
clinical and biological abnormalities of innate and adaptive circulating
immune cells potentially involving newly described functions of FcRn. In
this study, FcRn expression was measured by flow cytometry in leukocytes
of 41 SLE patients with either active or inactive disease and 32 healthy
donors. FcRn expression in B cells, natural killer cells, T cells of SLE
patients was statistically lower as compared to healthy donors.
Conversely, FcRn levels were statistically higher in non-classical
monocyte subpopulation (CD14+CD16+ monocytes) of SLE patients vs.
healthy donors. Non-classical monocytes are known to be involved in
organ damage in SLE. Thus, the higher expression of FcRn in these cells
could support the hypothesis of FcRn participation in the
pathophysiology of SLE, especially in lupus nephritis.