To evaluate the impact of heterogeneous B cells in health and disease, comprehensive profiling is needed at a single cell resolution. We developed a highlymultiplexed screen to quantify the co-expression of 351 surface molecules on low numbers of primary cells. We identified dozens of differentially expressed molecules and aligned their variance with B cell isotype usage, metabolism, biosynthesis activity, and signaling response. Here, we propose a new classification scheme to segregate peripheral blood B cells into ten unique subsets, including a CD45RB+ CD27-early memory population and a CD19 hi CD11c+ memory population that is a potent responder to immune activation. Furthermore, we quantify the contributions of antibody isotype and cell surface phenotype to various cell processes and find that phenotype largely drives B cell function. Taken together, these findings provide an extensive profile of human B cell diversity that can serve as a resource for further immunological investigations.
Introduction:B cells have a profound effect on human health. Their ability to create a diverse antibody repertoire protects against an ever-evolving landscape of pathogens, while the formation of immunological memory suppresses repeat infection. A robust antibody response is the primary goal of nearly all current vaccinations and remains as the best correlate of vaccine efficacy (Plotkin, 2010). B cells have, however, also been implicated in pathogenic roles in autoimmunity (Magro, Clair and Tedder, 2008), transplant (Karahan, Claas and Heidt, 2017), and cancer (Sarvaria, Madrigal and Saudemont, 2017). Indeed, targeting B cells with anti-CD20 therapy in each of these diseases has shown promising results (Huynh et al. 2017;Sood and Hariharan 2018; Thaunat, Morelon, and Defrance 2010), though it is not always clear whether the therapeutic benefits arise from mitigation of antibody generation or disruption of some alternative B cell function.Canonical gating strategies segregate B cells into five populations: transitional, naïve, non-switched memory, switched memory, and plasma cells (Maecker, 2012).Transitional cells (CD24 hi CD38 hi CD27-IgMD+) are recent bone marrow emigrants transitioning from immature to mature B cells. Naïve B cells (CD38 lo /-CD27-IgMD+) are mature B cells that are 'naïve' to antigen and have never been stimulated by their cognate antigen. Memory cells (CD38 lo /-CD27+) have taken part in previous immune responses and form part of the immunological memory of that event to prevent reinfection. These cells are further segregated as non-switched (IgM+ and/or IgD+) or switched IgM-, IgD-), based on their immunoglobulin heavy chain (IgH) isotypes which can 'switch' from the immature isotypes (IgM and IgD) to the mature isotypes (IgG, IgA, and IgE) after stimulation. Each antibody isotype confers unique downstream effector functions to membrane-bound and secreted antibodies and isotype usage can have both tissue-and pathogen-specific associations (Janeway et al., 2005). Plasma cells (CD38 hi CD27 hi ) also ...