Phenotypic signature of B cell subsets as a tool to investigate immunogenicity

It has recently become clear that different B cell subsets contribute to both the pathogenesis of immune disorders, as well as the maintenance of tolerance, and are therefore implicated in the development of autoimmunity. Patients with rheumatoid arthritis (RA) and systemic lupus erythematosus are characterized by an increase in pathogenic B cells (e.g. memory), and a decrease or functional impairment of regulatory B cells (Bregs), which promote tolerance via the production of interleukin-10. In humans, we and others have shown that B cells with suppressive capacity are enriched in the CD19+CD24hiCD38hi compartment. These cells can interrupt T cell-B cell positive feedback, suppress effector T cell proliferation, and induce regulatory T cell differentiation. Yet conclusive markers for the identification of a pure Breg population, distinct from those with pathogenic capacity, have not been found. Here we describe a new immunophenotyping platform, with which we can screen the expression of 242 cell-surface markers in parallel by flow cytometry. This has enabled us to generate a surface marker “signature” for different B cell subsets, and provided us with a phenotypic counterpart to gene array data. A major goal in the development of biopharmaceutical drugs is to predict which patients are likely to respond with anti-drug antibodies (ADAs) – one of the principal drawbacks of biological therapies. We will implement our method to compare B cell subset signatures in a longitudinal cohort of RA patients treated with anti-TNFa in order to identify predictive markers for those patients who will become ADA positive.