Background/Purpose: B cells are playing a major role in granulomatosis with polyangiitis (GPA, formarly known as Wegener’s disease). This is reflected by the presence of autoantibodies directed against neutrophil granular encymes ( ANCA) in a great majority of patients as well as in the success of B cell depleting therapies in GPA. Renal manifestations are directly mediated by autoantibodies. Whether mucosal plasma cells play a role in ENT-involvment is yet unknown. IgA-ANCA can be found in about 30% of GPA patients ( Kelley et al). For a better understanding of the possible role of B cells in GPA we analyzed B cells subsets in the peripheral blood of patients and found major changes correlating with disease activity (BVAS).
Methods: 18 patients with GPA ( 11 with active disease, 7 in remission) were analyzed by flow cytometry and compared to 17 healthy donors. Stainings for CD19, 20, 27, IgD, IgA and MHCII were performed and analyzed by FlowJo-software. The study was approved by the Charité ethics committee and all patients signed informed consent. Statistical analysis was performed using GraphPadPrism.
Results: Marked differences ( p=0,0018) were found regarding the number and frequency of plasmablasts and plasma cells in patients with active disease ( 6,4 ± 5,06/µl) as compared to patients in remission ( 2,5 ± 1,6/µl) or healthy donors ( 2,3 ± 1,2/µl). In patients with GPA a significant higher number of the plasma cells produced IgA as compared to healthy controls ( p=0,0028).
The number of plasma cells as well as their frequency correlate with disease activity ( r= 0,9135, p<0,0001). Interestingly, no expansion of the double negative memory B cells that has been described in SLE could be seen. For naive B cells significant differences could be detected as well.
Conclusion: The number of plasma cells in active GPA is increased. This implies a central role of plasma cells in the pathogenesis of GPA. A high frequency of these plasma cells is producing IgA, which could play a role in ENT-involvement. Further studies including the analysis of ENT biopsies are needed to further understand their role in disease pathogenesis.
Disclosure:
B. F. Hoyer,
None;
A. Taddeo,
None;
Q. Cheng,
None;
L. Khodadadi,
None;
G. Burmester,
None;
F. Hiepe,
None.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/expansion-of-iga-plasma-cells-as-a-sign-for-ear-nose-throat-involvment-in-granulomatosis-with-polyangiitis/