Age-Associated B Cells are Heterogenous and Dynamic in Autoimmunity

Age-Associated B Cells (ABCs) are a population of CD11c+ and/or CD11b+ B cells expanded in autoimmune lupus. To understand potential heterogeneity within ABCs and the relationship of ABCs to other splenic B cell subsets, we performed scRNA-seq with 5' V(D)J and CITE-seq cell surface features using the 10x Genomics Chromium platform on total splenic CD19+ B cells sorted from lupus-prone MRL/lpr. We found that ABC are a distinct transcriptional lineage that resolved into two related clusters. Analysis of BCR heavy chains identified clones present in both ABC and plasmablast compartments. Inferred lineage trees based on V gene somatic hypermutation suggested that self-renewing ABC feed into the plasmablast compartment repeatedly while continuing to themselves undergo mutation and expansion. scRNAseq data were generated from 3 female MRL/lpr mice at 18 weeks old