Background: Common variable immunodeficiency (CVID) is an inborn error of immunity characterized by disturbed immunoglobulin production. Despite of the terrain with severe antibody deficiency, autoantibody-mediated autoimmune phenomena belong to the most frequent autoimmune manifestation. However, many unresolved issues such as prevalence, clinical relevance and origin of autoantibodies detected in CVID patients receiving immunoglobulin replacement therapy (IRT) make the diagnostics of autoimmune complications difficult. Methods: A prospective observational study evaluating the spectrum of 38 different autoantibodies in 38 CVID patients receiving IRT, and in the immunoglobulin solutions used for IRT. Results: The study reveals a high prevalence of anti-GAD (55.3%) and anti-TPO (68.4%) autoantibodes in the cohort of 38 CVID patients on regular IRT. However, the titers of anti-GAD (3.22 vs. 22 kU/L, p≤0.0001) and anti-TPO (109.7 vs. 713 kU/L, p≤0.0001) were significantly lower compared to the newly diagnosed T1D and AIT patients. Moreover, none of the CVID patients with detectable antibodies manifested with T1D and only three patients became suspected of having AIT. A high quantity of anti-GAD (3.24-24.48 kU/L) and anti-TPO (123.6-156.55 kU/L) autoantibodies was found in immunoglobulin solutions for IRT. Conclusions: The study finds a very high prevalence of anti-GAD and anti-TPO autoantibodies in CVID patients receiving regular IRT. Nevertheless, the presence of anti-GAD and anti-TPO is not associated with the manifestation of the respective autoimmune disease. As the high titers of both anti-GAD and anti-TPO were also found in the therapeutics used for IRT, we suggest that the therapeutic immunoglobulins are the source of this false positivity.

Background: Common variable immunodeficiency (CVID) is characterized by an impaired post-vaccination response, high susceptibility to respiratory tract infections, and a broad spectrum of non-infectious complications. Thus, patients with CVID are at high risk of coronavirus disease 2019 (COVID-19), and vaccination’s role in prevention is questionable. The main aim of this study was to evaluate the clinical outcomes, safety, and dynamics of humoral and T-cell immune responses induced by the mRNA vaccine BNT162b2 in CVID. Methods: This prospective observational cohort study focused on the clinical outcomes (proportion of infected patients, disease severity), safety (adverse-event incidence, laboratory-parameter changes), and dynamics of humoral (specific post-vaccination and virus-neutralizing-antibody assessment) and T-cell immune responses (anti-SARS-CoV-2 specific T-cell detection) in 21 patients with CVID after a two-dose administration of BNT162b2. The patients were followed for 6 months. Results: Humoral response was observed in 52% (11/21) of patients at month 1 post-vaccination but continuously decreased to 33.3% (5/15) at month 6. Nevertheless, they had a remarkably lower anti-SARS-CoV-2 neutralizing antibody titer than healthy controls. The T-cell response was measurable in 33% (6/17) of patients with CVID at month 1, and it persisted for the study period. Mild infection occurred in three patients (14.3%) within the follow-up period. The vaccine also exhibited a favorable safety profile. Conclusions: The BNT162b2 vaccine elicited a measurable antibody response in a high proportion of patients, but it was limited by low titer of the virus-neutralizing antibodies and rapid waning of anti-RBD SARS-CoV-2 specific antibodies. T-cell response was detected in one-third of the patients and remained stable within the follow-up period. Vaccination has favorable safety and clinical-related outcomes in preventing severe COVID-19.