Transcriptomic analysis of double-negative B cell subsets in IgG4-related disease

IgD-CD27- “double negative” (DN) B cells are known to be expanded in the blood in many disease contexts and the IgD-CD27-CXCR5-CD11c+ DN2 B cell subset has been most widely studied in autoimmune diseases. In addition to DN2 B cells, a distinct IgD-CD27-CXCR5-CD11c- DN3 B cell subset accumulates in the blood both in IgG4-related disease, an autoimmune disease in which inflammation and fibrosis can be reversed by B cell depletion, and in severe COVID-19. DN3 B cells, but not DN2 B cells, prominently accumulate in the blood and end-organs of IgG4-related disease. Total RNA was extracted from IgD-CD27- double negative (DN) B cell subsets from subjects with IgG4-related disease and subjected to mRNA sequencing using the SmartSeq2 protocol. IgD-CD27- DN B cell subsets were defined using the following flow cytometry markers: DN1: CXCR5pos CD11Cneg DN2: CXCR5neg CD11Cpos DN3: CXCR5pos CD11Cpos DN4: CXCR5neg CD11Cneg