B cell-intrinsic IFN-γ promotes excessive CD11c+ age-associated B cell differentiation and compromised germinal center selection in lupus mice

CD11c⁺ age-associated B cells (ABCs) have emerged as a key component in protective and autoreactive B cell responses. Lupus is an autoimmune disorder linked to reduced efficacy of vaccines and increased susceptibility to infections. Previously, we reported that excessive CD11c⁺ ABCs not only significantly contribute to autoantibody production but also promote aberrant T cell activation and compromised affinity-based germinal center selection in response to immunization in lupus mice. Yet, the regulation of CD11c⁺ ABC differentiation is not fully understood. In this study, we show that B cell-intrinsic IFN-γ is required for excessive CD11c⁺ ABC differentiation in lupus mice. B cell-intrinsic IFN-γ is mainly produced by CD11c⁺ ABCs. IFN-γ-deficiency leads to decreased expression of ABC characteristic genes. We further show that ablating IFN-γ can normalize T cell overactivation and rescue antigen-specific GC responses in lupus mice. Our study offers insight into the crucial role of B cell-intrinsic IFN-γ in promoting excessive CD11c⁺ ABC differentiation, which compromises affinity-based germinal center selection and affinity maturation in lupus, providing a potential strategy to normalize vaccine responses in lupus.