Autoimmunity

Membranous nephropathy (MN) is a kidney specific autoimmune disease mainly mediated by anti-phospholipase A2 receptor 1 autoantibody (PLA2R1 Ab). The adequate assessment of chimeric anti-CD20 monoclonal antibody, rituximab (RTX) efficacy is still needed to improve clinical outcome of patient with MN. We evaluated the modification of plasmablasts (CD3-CD19+CD20-IgD-CD27highCD38high), a useful biomarker of RTX response in other autoimmune diseases, memory (CD3- CD19+CD20+IgD-CD27+CD38-) and naive (CD3-CD19+CD20+IgD+CD27-CD38low) B cells by fluorescence-activated cell sorter analysis in PLA2R1 related MN in one patient during 4-years of follow-up after RTX. RTX induced complete disappearance of CD19+ B cells, plasmablasts and memory B cells as soon as day 15. Despite of severe CD19+ lymphopenia, plasmablasts and memory B cells re-emerged early before naive B cells (days 45, 90 and 120, respectively). During the follow-up, plasmablasts decreased more rapidly than memory B cells but remained still elevated as compared to Day 0 of RTX. Concomitantly, anti- PLA2R1 Ab increased progressively. Our single case report suggests that besides monitoring of serum anti-PLA2R1 Ab level, enumeration of circulating plasmablasts and memory B cells represents an attractive and complementary tool to assess immunological activity and efficacy of RTX induced B cells depletion in anti-PLA2R1 Ab related MN.