Patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) may have circulating B cells with modified receptor expression as well as altered serum levels of B-cell activation factor of the TNF family (BAFF) and a proliferation-inducing ligand (APRIL), according to an article recently published in the journal Clinical and Experimental Immunology.
Researchers collected blood samples from 24 patients with active AAV, 13 patients with inactive AAV, and 19 healthy individuals. They used flow cytometry to analyze the proportion of B cells and their expressing BAFF receptor, transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI), and B-cell maturation antigen. Enzyme-linked immunosorbent assay was used to measure serum levels of BAFF, APRIL, and interleukin (IL)-4, IL-6, IL-10, and IL-13.
According to the results, the proportion of plasmablasts/plasma cells and serum levels of BAFF, APRIL, IL-4, and IL-6 were significantly increased in people with active AAV compared with healthy controls. Moreover, people with the inactive disease had higher serum levels of BAFF, APRIL, and IL-4 than healthy participants.
Lower expression of BAFF receptors on memory B cells and higher expression of TACI on CD19+ cells, immature B cells, and PB/PC were demonstrated in patients with active and inactive AAV, as compared with healthy controls.
“Decreased expression of BAFF receptors on memory B cells and increased expression of TACI on CD19+ cells, immature B cells, and PB/PC, as well as increased serum levels of BAFF and APRIL, were sustained even in the remission phase of AAV. Persistent aberrant signaling of BAFF/APRIL may contribute to disease relapse,” Shimojima and colleagues noted.
AAV has been associated with a number of genetic and environmental factors, such as exposure to pollutants, drugs, and microbial infections, although the exact biological mechanisms underpinning this autoimmune disease are not entirely clear.
Reference
Shimojima Y, Kishida D, Ichikawa T, Takamatsu R, Nomura S, Sekijima Y. Features of BAFF and APRIL receptors on circulating B cells in antineutrophil cytoplasmic antibody-associated vasculitis. Clin Exp Immunol. Published online February 16, 2023. doi:10.1093/cei/uxad024
