AB1324 DIFFERENCES IN PERIPHERAL BLOOD B-CELL SUBSETS IN PATIENTS WITH IGG4-RELATED DISEASE, PRIMARY SJOGREN’S SYNDROME AND HEALTHY DONORS

Abstract

BackgroundThe level of circulating plasmablasts has been proposed as a good marker for diagnosing and monitoring IgG4-related disease (IgG4-RD) independent of serum IgG4 level [1]. However elevated plasmablasts can be seen in other rheumatologic conditions.ObjectivesTo compare В-cell subsets in peripheral blood of IgG4-RD, Sjogren’s syndrome (SjS) patients (pts) and healthy controls.MethodsTwelve pts with clinically active IgG4-RD (7F/5M, mean age 50,25 years (range 33-62), 20 active SjS pts (19F/1M, mean age 42 years (range 32-54 years); median disease duration 3 (2-10) years; ESSDAI score ≥5 in 6 pts,) and 20 healthy donors were included. SS was diagnosed based on the ACR-EULAR 2016 criteria. IgG4-RD was diagnosed according to comprehensive diagnostic criteria (H. Umehara, 2011). CD19+ B cells, memory B-cells (CD19+CD27+), non-switched memory B-cells (CD19+IgD+CD27+), switched memory B-cells (CD19+IgD-CD27+), naïve (CD19+IgD+CD27-), double negative (CD19+IgD-CD27-), transitional (CD19+IgD+CD10+CD38+) B-cells, plasmablasts (CD19+СD38+++IgD-CD27+), and plasma cells (CD19+СD38+) were analyzed by multicolor flow cytometry using cytometer Navios (Beckman Coulter, USA). The nonparametric Mann-Whitney test was used for statistical analysis. Data were shown as median (Me) with an interquartile range of 25 - 75 percentile. The differences were considered statistically significant when p <0.05. Statistica 10 for Windows (StatSoft Inc., USA) package was used for statistical data processing.ResultsThere were no significant differences in the number of all studied B-cell subsets between pts with IgG4-RD and with SjS. But absolute numbers of plasmablasts, memory B-cells cells and transitional B-cells in IgG4-RD were significantly higher than in healthy donors: 4.5[1;9.8] х103/μl vs. 0.2 [0.09;0.4] х103/μl; 41 [33.5;57.5] х103/μl vs. 2.5 [1;6.3]; 12 [6.5;21] х103/μl vs. 0.1 [0;0.23] х103/μl respectively, p<0.05 for all cases.Table 1.Peripheral blood B-cell subsets in patients with SS and healthy donors.B-cell subsets,IgG4-RDSjSHDP<0.05Abs. х103/μlB lymphocyte166 [109.3;251.3]164.5 [109.3;236.3]150 [95;200]plasmablasts4.5 [1;9.8]2 [1;3.5]0.2 [0.09;0.4]*transitional B-cells12 [6.5;21]8.5 [4;32.5]0.1 [0;0.23]*switched cells24.5 [20;41.8]18.5 [11;29.8]20 [9.75;40]non-switched cells16.5 [10.5;21]7 [3.75;15.5]10 [4.75;20]memory B-cells41 [33.5;57.5]26 [14.8;40.8]2.5 [1;6.3]*naïve B-cells122 [63.3;176.5]107.5 [49.5;193.8]100 [57.5;100]double negative13.5 [8.8;17]10.5 [5.3;22.3]20 [9.75;22.5]HD healthy donors* IgG4-RD and HD groups compared, р<0.05ConclusionImmunophenotyping showed disturbed homeostasis of the B-cells subpopulations in IgG4-RD pts with a significant increase in plasmablasts compared to HD, but there were no differences between IgG4-RD and SjS pts. Further research is needed to evaluate the diagnostic utility of circulating plasmablasts in IgG4-RD.