Abstract
Aim Monitoring the prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) immunization in patients with autoimmune diseases is of particular concern to understand their response to the infection and to the vaccine. In fact, the immunological disorder and the immunosuppressive therapies could affect the serological response. SARS-CoV2 serological tests potentially provide this information, although they were rapidly commercialized with internal verifications. Here, we analysed the seroprevalence to SARS-CoV2 in a cohort of patients with liver autoimmune diseases. Methods From May to December 2020, a cohort of patients affected by primary biliary cholangitis (PBC), autoimmune hepatitis (AIH) and PBC/AIH overlap syndrome were screened with (reverse transcription-polymerase chain reaction) RT-PCR of nasopharyngeal swabs, rapid antigenic test and chemiluminescent serological test during routine follow-up. Results The analysis of 42 patients was carried out: 18 (42.85%) PBC, 12 (28.57%) AIH and 12 (28.57%) PBC/AIH overlap syndromes. Only 2 patients (4.76%) resulted positive to the RNA, antigen and antibody detection tests, hence affected by SARS-CoV2 infection. 14 subjects out of 40 negative cases presented a positive serology for SARS-CoV2 antibodies, hence with a false positivity in the 35% of cases without infection. Among these, 6 (42.86%) patients presented only immunoglobulin (Ig)M positivity, 6 (42.86%) patients presented positivity for only IgG and 2 (14.28%) patients were positive to both IgM and IgG. Notably, the presence of autoantibodies did not correlate with the serological false positivity, highlighting that there is no cross-reactivity with autoantibodies. The presence of polyclonal hypergammaglobulinemia did not interfere with the serological test as well. Interestingly, the patients with false positive serology showed higher levels of gamma-glutamyltransferase (GGT) and C-reactive protein (CRP). Conclusions Patients with liver autoimmune diseases present a high rate of false positive SARS-CoV2 serology. Therefore, new strategies are needed to study the serological response in this patient category.
Highlights
The coronavirus disease 2019 (COVID-19), first reported in Wuhan (China) in December 2019, has become a global pandemic which caused more than 170 million cases and 3.5 million deaths to date [1]
2 patients (4.76%) resulted positive to the RNA, antigen and antibody detection tests, affected by SARS-CoV2 infection. 14 subjects out of 40 negative cases presented a positive serology for SARS-CoV2 antibodies, with a false positivity in the 35% of cases without infection
The presence of autoantibodies did not correlate with the serological false positivity, highlighting that there is no cross-reactivity with autoantibodies
Summary
The coronavirus disease 2019 (COVID-19), first reported in Wuhan (China) in December 2019, has become a global pandemic which caused more than 170 million cases and 3.5 million deaths to date [1]. The rapid and accurate diagnosis is crucial to stop its widespread. The diagnosis of COVID-19 is still a challenge as symptoms are not disease specific (e.g., fever, cough, and fatigue) [2]. The main available weapons to identify severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) infection are the viral RNA detection by reverse transcription-polymerase chain reaction (RT-PCR) of nasopharyngeal swabs and the serum antibody detection [3]. The sensitivity of RT-PCR depends on the RNA amount in the sample, permitting to classify patients as “positive” or “negative” cases. Reliable antibody detection methods are crucial for the identification of plasma donors, human mobility permission and development of vaccine strategies
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