Abstract: TH-PO0446
Endocapillary Hypercellularity and Proliferating Intraglomerular Macrophages in Clinically Refractory Pediatric IgA Vasculitis Nephritis (IgAVN)
Session Information
- Glomerular Diseases: Autoimmune Diseases
October 22, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1401 Glomerular Diseases: Mechanisms, including Podocyte Biology
Authors
- Ikezumi, Yohei, Fujita Health University School of Medicine Department of Pediatrics, Toyoake, Japan
- Ando, Takuma, Fujita Health University School of Medicine Department of Pediatrics, Toyoake, Japan
- Kondo, Tomomi, Fujita Health University School of Medicine Department of Pediatrics, Toyoake, Japan
- Matsumoto, Yuji, Fujita Health University School of Medicine Department of Pediatrics, Toyoake, Japan
- Kumagai, Naonori, Fujita Health University School of Medicine Department of Pediatrics, Toyoake, Japan
Background
Pediatric IgA vasculitis nephritis (IgAVN) can be severe and treatment-resistant despite intensive therapy such as methylprednisolone pulse therapy (MPT) and cyclosporine A (CsA). We examined clinicopathologic features of MPT/CsA-resistant IgAVN and pathology-based rationale for cyclophosphamide (CYC).
Methods
We retrospectively reviewed 25 biopsy-proven pediatric IgAVN cases with ISKDC grade ≥III. Five cases refractory to MPT and CsA that achieved remission after cyclophosphamide (CYC) (refractory/CYC group) were compared with 20 cases achieving remission without CYC (non-refractory group). Clinical variables and histology, including intraglomerular CD68+ macrophage counts, were analyzed; double immunostaining for CD45/PCNA and CD68/PCNA was performed in refractory cases.
Results
Age at onset/biopsy, kidney function at biopsy, proteinuria, and hematuria were similar between groups, whereas the onset-to-biopsy interval was shorter in the refractory/CYC group. Mesangial changes, the proportion of glomeruli with crescents, and glomerulosclerosis did not differ; however, endocapillary proliferative lesions with capillary lumen narrowing/occlusion were more frequent in the refractory/CYC group (77.3% vs 36.7%, p<0.01). Intraglomerular CD68+ macrophages were higher (13.0 vs 7.7 per glomerulus, p<0.05) and correlated with the number of glomeruli showing lumen narrowing/occlusion (r=0.73, p<0.001). PCNA+CD45+ proliferating leukocytes were present within glomeruli, most of which were CD68+ macrophages.
Conclusion
Although ISKDC grading is based on crescent extent, prominent endocapillary hypercellularity may be associated with treatment resistance. The predominance of proliferating intraglomerular macrophages suggests a potential cellular target of the alkylating agent CYC, which may be useful for inducing remission in pediatric severe IgAVN characterized by marked endocapillary proliferative lesions with capillary lumen narrowing/occlusion.
Acknowledgment
This work was supported by JSPS KAKENHI Grant Number JP24K10988 to YI.
Funding
- Government Support – Non-U.S.