B cell abnormalities in Wegener's granulomatosis and microscopic polyangiitis: role of CD25+-expressing B cells.
OBJECTIVE
The use of rituximab in vasculitis has increased interest in B cell biology. A subpopulation of B cells expressing CD25 shows antigen-presenting properties and may have regulatory functions. We assessed subpopulations of B cell maturation (Bm) and markers related to activity and antigen presentation, and related the findings to disease activity.


METHODS
Multiparameter flow cytometry was used to assess numbers and proportions of circulating lymphocytes from 34 patients with vasculitis (16 remission, 18 active) and 20 controls.


RESULTS
Active vasculitis samples showed decreased proportions of Bm1 (7.8% vs 11%; p = 0.041), Bm2' (0.2% vs 0.7%; p = 0.002), and Bm3/Bm4 (0.1% vs 0.3%; p = 0.006), compared with controls; Bm2 cells were the most frequently occurring B cells but they were not significantly different in active vasculitis (74% vs 62%; p = 0.083). In patients with remission the proportion of CD25+ B cells was increased compared to controls (48% vs 29%, respectively; p = 0.006) and also compared to active vasculitis (23%; p = 0.006). The proportion of CD86+ B cells was also increased (31%) compared to active vasculitis (8%; p = 0.001), and to controls (6%; p = 0.0003). In multivariate analysis, Bm2' cells and CD25+27- B cells were independently influencing the patient group.


CONCLUSIONS
In active vasculitis, a lower proportion of Bm1 cells may indicate activated B cells. Patients in remission had higher proportions of CD25+ (α-chain of interleukin 2 receptor) and CD86+ (costimulatory molecule) B cells. We suggest that these B cells may have a regulatory role, or alternatively may result from previous treatment.
Eriksson
Per
P
Department of Rheumatology, University Hospital, Linköping University, Linköping, Sweden. per.eriksson@lio.se
Sandell
Christina
C
Backteman
Karin
K
Ernerudh
Jan
J
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D005260:Female; D014890:Granulomatosis with Polyangiitis / Q000276:immunology* / Q000503:physiopathology; D006801:Humans; D053645:Interleukin-2 Receptor alpha Subunit / Q000276:immunology*; D016131:Lymphocyte Subsets / Q000276:immunology*; D008297:Male; D055953:Microscopic Polyangiitis / Q000276:immunology* / Q000503:physiopathology; D008875:Middle Aged
C508017:IL2RA protein, human; D053645:Interleukin-2 Receptor alpha Subunit