Background/Purpose: Adult-onset Still’s Disease (AOSD) is a rare autoinflammatory disorder characterized by high fever, rash, and arthritis. Although overactivation of macrophages, an increase in specific neutrophils, disruption of Th17/Treg cell balance, and decreased NK cell function have been reported in the pathogenesis of AOSD, the detailed roles and interactions of these immune cells in various aspects of the disease pathogenesis remain unclear. This study aimed to identify disease-related cell populations through comprehensive immunophenotyping analysis by mass cytometry.

Methods: Mass cytometry of peripheral whole blood was performed using 50 samples from patients with AOSD (six untreated active and forty-four in clinically inactive disease [CID]) and 21 control samples from healthy subjects (HC). Whole blood was stained with Maxpar Direct Immune Profiling Assay from Standard BioTools which contains antibodies of 30 markers and measured by Helios. The data was analyzed in Cytobank from Beckman Coulter. Dimensionality reduction and clustering analysis was performed using tSNE-CUDA and FlowSOM.

Results: The proportions of B cells, NK cells, and gamma delta T cells were significantly decreased in the active AOSD group compared to the HC group. These changes in cell subset proportions were persistent even after achieving CID. For more detailed analysis, we used FlowSOM clustering to divide those cells into 400 clusters. In the active AOSD group, the proportions of 66 clusters were significantly higher compared with the HC group. Among the increased cell clusters, 21 clusters were not different between the CID and HC groups, including CD4 cells, CD8 cells, monocytes, neutrophils, and eosinophils. Based on the expression patterns, the monocytes were characterized as intermediate monocytes with upregulated CD11c and HLA-DR and downregulated CD38. The CD4 cells exhibited features of effector memory cells, characterized by upregulation of CXCR3, CCR4, CD28, CD38, and HLA-DR, along with downregulation of CD27 and CD127. Similarly, the CD8 cells were also classified as effector memory cells, showing upregulation of CXCR3, CD27, CD28, CD38, and HLA-DR, and downregulation of CD57 and CD127.

Conclusion: Comprehensive and detailed mass cytometry analysis of peripheral blood cells from patients with AOSD identified characteristic intermediate monocytes and effector memory T cells were increased in the active phase and normalized after achieving CID. Those cell subsets may play an important role in the pathogenesis of AOSD and can be a new therapeutic target.

Dimensionality reduction by tSNE-CUDA in mass cytometry data of peripheral blood cells

Cell subsets increased in untreated active AOSD and normalized upon CID

Heatmap of marker expression in cell subsets normalized upon CID

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/comprehensive-mass-cytometry-analyses-of-disease-related-cells-in-adult-onset-stills-disease/