POS1441 OCULAR AND PERIPHERAL BLOOD IMMUNE PHENOTYPES SUGGEST TRANSMIGRATION OF CD16+ MONOCYTES TO AN IMPORTANT EFFECTOR SITE IN BEHÇET’S DISEASE

Background Cellular immunity of Behçet’s Disease (BD) remains poorly understood. Previous work has provided clues pointing to most innate and adaptive immune cell types in BD, but strong signals from non-immunogenetic studies are rare often inconclusive. Objectives Here we aimed identify BD/HD discriminant single profiles semi-biased targeted approaches determine their significance at a BD relevant effector site. Methods We utilized multi-parametric flow cytometry dissect cellular phenotypes PBMC untreated patients (n=27) HD (n=22) consisting predominantly active ocular major vascular subjects. Data were subjected supervised machine learning (CITRUS) results verified with gating. also analyzed anterior chamber (AC) fluid cells autologous uveitis subjects scRNA seq. Results CITRUS identified CD16+, CD14low, CD4low, CD3-, CD19- as distinguishing expression pattern an FDR >0.05. Targeted gating confirmed highly significant differences large effect sizes vs for “non-classical” (CD14lowCD16hi) “intermediate” (CD14+CD16+) monocytes decreased frequencies compared peripheral blood. “Classical” (CD14++CD16-) more abundant than HD. CD16+ dendritic (DC) significantly PBMC. CD14+ showed high abundance the AC during co-expressed CD16 far frequently Conclusion Significantly lower monocyte DC subsets strongly point importance BD. The co-expression eye relative frequency blood, suggests transmigration or post-migrational interconversion within rather stochastic process. REFERENCES: NIL. Acknowledgements: Disclosure Interests Yesim Ozguler: None declared, Ziyan Lin: Gulen Hatemi: Ann Cavers: Johannes Nowatzky Grant/research support from: NIH-NEI R01EY031383 (Nowatzky), R01EY033495 (Nowatzky)