Beyond B cells: T and Innate Immune Mechanisms of Autoimmunity in Common Variable Immunodeficiency

Abstract

Common variable immunodeficiency (CVID) is the most prevalent symptomatic primary immunodeficiency, affecting approximately 1 in 25 000–50 000 individuals. Although classically characterized by hypogammaglobulinemia and recurrent bacterial infections, over 50% of patients develop non-infectious complications that constitute the major determinants of morbidity and mortality. The coexistence of immunodeficiency and immune dysregulation challenges the traditional B-cell-centric model of CVID pathogenesis. In this narrative review, we synthesize current evidence demonstrating that autoimmune manifestations in CVID arise from complex, multilayered immune dysfunction extending far beyond the B-cell compartment. Key abnormalities include Th1-skewed CD4⁺ T-cell responses with persistent IFN-γ production, numerical and functional defects in regulatory T cells, disruption of follicular T-cell subset balance favoring autoreactive germinal center responses, and progressive CD8⁺ T-cell exhaustion. At the innate immune level, NK-cell lymphopenia, constitutive monocyte activation, dendritic cell deficiency, neutrophil dysregulation, and proinflammatory innate lymphoid cell activity collectively contribute to the breakdown of self-tolerance. These immune perturbations are further amplified by systemic cytokine dysregulation. Pathogenic variants identified in patients with CVID-like disorders may further underlie autoimmune pathology and immune dysregulation, particularly those affecting T-cell co-stimulation, immune checkpoint signaling, NF-κB, and PI3K pathways. Collectively, CVID-associated autoimmunity represents a paradigm of systems-level immune dysregulation, underscoring the need for comprehensive immune phenotyping, genotype-informed stratification, and precision immunomodulatory strategies targeting the full spectrum of immune abnormalities involved.