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During the congress, E-Posters will be accessible to all participants on the congress website 24/7, as well as in the E-poster stations in the congress center.
Preparing your E-Poster
Please review the E-Poster format requirements carefully when preparing your E-Poster. Should your E-Poster not meet the mentioned requirements, it may not be displayed as described above.
E-Poster Submission Deadline
Please prepare and upload your E-Poster no later than March 14, 2026 11.59PM CET. After this date, you will no longer be able to prepare and upload your E-poster and it will not be displayed and accessible on the congress website.
Please follow the instructions below to input your abstract title.
Abstract titles should be brief and reflect the content of the abstract.
We previously reported that serum of IgAN patients contain anti-mesangial IgA antibodies that react with mesangial cells (Sci. Adv. 2023; Life Sci. Alliance 2024). The hinge-region O-linked glycans of purified anti-mesangial IgA antibodies from patients’ serum lacked galactose, indicating that these antibodies represent pathogenic Gd-IgA1 (Kidney Int. Rep. 2025). Recently, anti-APRIL antibodies have shown therapeutic efficacy in IgAN (N Engl J Med. 2024; Kidney Int. 2025), suggesting that nephritogenic IgA antibodies may be supplied by long-lived plasma cells (LLPCs). However, relapse following discontinuation of anti-APRIL therapy in some patients suggests that LLPCs producing nephritogenic IgA antibodies might be replenished by memory B cells (MBCs). In this study, we investigated whether patients with IgAN possess MBCs producing anti-mesangial IgA antibodies.
Among 32 IgAN patients who underwent tonsillectomy at Juntendo University between October 2024―August 2025, we selected those with high titers of anti-mesangial IgA antibodies in serum or tonsillar mononuclear cell (TMNC) culture supernatants. IgA1⁺ MBCs (CD19⁺, IgM⁻, IgG⁻, CD27⁺, CD38⁻, IgA1⁺) were isolated as single cells into 384-well plates by flow cytometry and cultured. After 2 weeks, IgA and anti-β2 spectrin IgA antibody production in the culture supernatants was assessed by ELISA.
We first established a culture system in which IgA antibody production from single MBCs could be detected in the supernatant. Irradiated 40LB cells (BALB/c-3T3 fibroblasts transduced to express CD40 ligand and BAFF) were coated into ELISA plates, and individual MBCs were seeded onto irradiated 40LB cells(BALB/c-3T3 fibroblasts transduced to express CD40 ligand and BAFF) (Nat Commun. 2011). MBCs were co-cultured with these feeder cells, expanded with IL-2 and IL-21 until day 5, followed by secondary stimulation with IL-6, IL-10, APRIL, BAFF, transferrin, and ODN2006 to induce differentiation into plasmablasts—the two-step culture protocol. In this system, approximately 45% of wells containing a single sorted MBC showed IgA positivity in the supernatant (5.7–500 ng/mL; mean 21.9 ng/mL). In MBC culture wells derived from IgAN patients whose TMNC supernatants contained anti-β2 spectrin or anti-CBX3 IgA antibodies, the corresponding specific antibodies were also detected.
This study demonstrated the presence of memory B cells producing anti-mesangial IgA antibodies in patients with IgAN. These findings suggest that anti-mesangial IgA antibodies may be maintained by both memory B cells and long-lived plasma cells.
