Single-cell mass cytometry on peripheral blood identifies immune cell subsets associated with primary biliary cholangitis

The relationship between primary biliary cholangitis (PBC), a chronic cholestatic autoimmune liver disease, and the peripheral immune system remains to be fully understood. Herein, we performed the first mass cytometry (CyTOF)-based, immunophenotyping analysis of the peripheral immune system in PBC at single-cell resolution. CyTOF was performed on peripheral blood mononuclear cells (PBMCs) from PBC patients (n=33) and age-/sex-matched healthy controls (n=33) to obtain immune cell abundance and marker expression profiles. Hierarchical clustering methods were applied to identify immune cell types and subsets significantly associated with PBC. Subsets of gamma-delta T cells (CD3(+)TCRgd(+)), CD8(+) T cells (CD3(+)CD8(+)CD161(+)PD1(+)), and memory B cells (CD3(-)CD19(+)CD20(+)CD24(+)CD27(+)) were found to have lower abundance in PBC than in control. In contrast, higher abundance of subsets of monocytes and naive B cells were observed in PBC compared to control. Furthermore, several naive B cell (CD3(-)CD19(+)CD20(+)CD24(-)CD27(-)) subsets were significantly higher in PBC patients with cirrhosis (indicative of late-stage disease) than in those without cirrhosis. Alternatively, subsets of memory B cells were lower in abundance in cirrhotic relative to non-cirrhotic PBC patients. Future immunophenotyping investigations could lead to better understanding of PBC pathogenesis and progression, and also to the discovery of novel biomarkers and treatment strategies.