Secondary lymphoid organs (SLOs) provide the confined microenvironment required for stromal cells to interact with immune cells to initiate adaptive immune responses resulting in B cell differentiation. Here, we studied three patients from two families with functional hyposplenism, absence of tonsils, and complete lymph node aplasia, leading to recurrent bacterial and viral infections. We identified biallelic loss-of-function mutations in LTBR, encoding the lymphotoxin beta receptor (LTβR), primarily expressed on stromal cells. Patients with LTβR deficiency had hypogammaglobulinemia, diminished memory B cells, regulatory and follicular T helper cells, and dysregulated expression of several tumor necrosis factor family members. B cell differentiation in an ex vivo coculture system was intact, implying that the observed B cell defects were not intrinsic in nature and instead resulted from LTβR-dependent stromal cell interaction signaling critical for SLO formation. Collectively, we define a human inborn error of immunity caused primarily by a stromal defect affecting the development and function of SLOs.

CTLA-4 is a critical immune checkpoint that maintains self-tolerance by regulating immune activation. Here, we describe the first case of homozygous CTLA-4 deficiency (CTLA4S172P/S172P), presenting with early-onset autoimmunity, lymphoproliferation, and growth failure. Immunological profiling revealed profound T- and B-cell dysregulation, characterized by T-cell hyperproliferation, a TH1-skewed helper T-cell phenotype, and expansion of activated and atypical B-cell subsets. The identified variant led to impaired CTLA-4 protein stability and enhanced lysosomal degradation, resulting in significantly reduced but still detectable total and surface expression and defective CD80 transendocytosis. Abatacept (CTLA-4-Ig) therapy effectively restored immune regulation and controlled disease activity. These findings expand the clinical and mechanistic spectrum of CTLA-4–related disorders, linking residual CTLA-4 function with the severity of immune dysregulation and emphasizing the therapeutic potential of targeted CTLA-4 modulation.

Introduction: Hereditary angioedema due to C1 inhibitor deficiency (HAE-C1INH) has a substantial impact on patients’ health-related quality of life (HRQoL). While generic instruments are frequently used for assessment, they may not fully capture the disease-specific burden. This study aimed to evaluate HRQoL in patients with HAE-C1INH types I and II using validated, angioedema-specific tools. The aims of the study were to assess HRQoL and disease control in patients with HAE-C1INH using validated angioedema-specific tools and secondarily to explore the association between attack localization and domain-specific quality-of-life impairments. Methods: In this multicenter cross-sectional study, 82 patients with HAE-C1INH from six referral centers completed the Angioedema Control Test (AECT), Angioedema Activity Score (AAS)-28, and Angioedema Quality of Life questionnaire (AE-QoL). Family screening was conducted among those who consented. Results: Patients experiencing attacks in the extremities (p < 0.001) and laryngeal/pharyngeal regions (p = 0.028) had significantly lower AECT scores, indicating poorer disease control. Higher AAS-28 scores were associated with attacks in the extremities (p = 0.008), abdomen (p = 0.018), face/neck (p = 0.004), larynx/pharynx (p < 0.001), and tongue/uvula/palate (p < 0.001). AE-QoL scores revealed impaired quality of life across all attack locations. Subdomain analysis showed that abdominal attacks significantly impacted the functioning (p = 0.005) and food (p = 0.037) domains. Attacks involving the face/neck and larynx/pharynx were associated with substantial impairment in fatigue/mood (p = 0.002, p = 0.003), functioning (p = 0.044, p = 0.002), and fears/shame (p = 0.039, p = 0.005) subdomains. Conclusion: While attack frequency and disease control remain the primary determinants of HRQoL in HAE-C1INH, our findings indicate that attack localization is associated with distinct domain-specific quality-of-life impairments. Beyond assessing attack frequency, the use of disease-specific QoL tools allows for the identification of domain-specific impairments. Personalized treatment strategies targeting both symptom control and quality-of-life domains are essential for alleviating the long-term burden on patients and their families.

Ejmi Eurasian Journal of Medical Investigation