Objectives To study B-cell subpopulation dynamics in SLE patients following Rituximab (RTX) therapy.
Methods The study included 31 SLE pts (3m/28f) with high (SLEDAI2K≥10–28 pts.) and moderate (SLEDAI2K<10–3 pts.) disease activity; out of them 12 pts with SLE nephritis, 5 pts with neurolupus and 8 with vasculitis. RTX was administered to pts who failed to respond to glucocorticoids (GCs) and cytostatics (CTs). B-cells subpopulations were assessed before RTX administration (Mo0), and at Mo3 and Mo6 of RTX therapy. RTX was administered at 500 to 2000 mg doses depending on disease activity. The absolute counts of CD19+ B-cells, the total population of memory B-cells (CD19+CD27+), “preswitch” (CD19+IgD+CD27+) and “postswitch” (CD19+IgD-CD27+) memory B-cells, “naive” (CD19+IgD+CD27-), plasma cells (CD19+CD38+) and double negative B-cells (CD19+CD27-IgD) were measured. All B cell subsets were analyzed with multicolor flow cytometry using a panel of monoclonal antibodies to B-lymphocytes' surface membrane markers.
Results Following initiation of RTX SLE clinical and lab activity indices have decreased in all 31 pts by Mo3 and Mo6 of follow up (SLEDAI-2K Mo0–Me 15 [12;18], Mo3-Me 6 [4;10], Mo6–Me 4 [2;8]), as well as absolute count CD19+ B-cell population (Mo0–Me 0,119x109/l [0,05;0,26], Mo3–Me 0x109/l [0;0,003], Mo6-Me 0,004x109/l [0;0,02]). B-cell repopulation by Mo6 in 15 out of 31 pts without signs of relapse and 4 pts with earlier relapse SLE was dependent on “naïve” B-cells (Me 0,0015x109/l [0,0002;0,01] vs Me 0,006x109/l [0,0033;0,008]), double negative (Me 0,001x109/l [0,0002;0,002] vs Me 0,0035x109/l [0,0018;0,005]) “postswitch” (Me 0,0005x109/l [0,00008;0,003] vs Me 0,0012x109/l [0,0003;0,0035]) and “preswitch” memory B-cells (Me 0,0006x109/l [0,00007;0,001] vs Me 0,0023x109/l [0,0005;0,005]).
Conclusions Decrease in clinical and lab SLE activity was documented in all 31 pts by Mo3 after one course of RTX therapy. In 4 pts with earlier relapse SLE at Mo6 B-cell was found repopulation and significant increase “naïve” B-cells, double negative, “postswitch” and “preswitch” memory B-cells compared with the group without relapse.
Disclosure of Interest None declared