Virus-specific humoral immune response in Bulgarian COVID-19 patients with varying disease severity.

INTRODUCTION: Our study aimed to analyze virus-specific humoral immune responses in COVID-19 patients with varying disease severity. METHODOLOGY: A total of 109 serum samples from 87 patients, symptomatic for COVID-19 were studied using anti-SARS-CoV-2 immunoassays detecting different classes of immunoglobulins. RESULTS: Clinical samples were divided into 2 groups - collected up to and more than 2 weeks post-onset of symptoms (PoS). In the first group, the highest percentage of positive samples was found for IgA class virus-specific antibodies (78.1%), followed by IgM (71.9%/59.4%) and IgG (56.3%/53.1%). In the second group, samples positive for virus-specific IgA class antibodies were also the most (97.7%) along with those positive for IgG. A total of 72 IgA and/or IgM and/or IgG positive samples were further tested for SARS-CoV-2 neutralizing antibodies (NAbs) - 89.1% and 100% of samples obtained up to and after 2 weeks PoS, respectively were positive. Serological test results were also analyzed depending on the severity of the disease - SARS-CoV-2 positive samples in mild forms of COVID-19 were fewer than in moderate and severe forms but this difference was not statistically significant. CONCLUSIONS: SARS-CoV-2 specific antibodies and a high virus neutralization capacity of these antibodies appear early PoS; Immunoglobulins of IgA class are of most significant diagnostic value for detection of SARS-CoV-2 infection; Timing of testing is the most important factor for positivity rate.

Mild to moderate clinical course of COVID-19 infection in patients with common variable immune deficiency.

The association of immunocompromised patients and severity of COVID-19 infection is not well established. According to the Centers for Disease Control and Prevention (CDC), primary immune deficiencies (PIDs) are among the conditions that can predispose to a more severe course of COVID-19. We report the clinical course and immunological evaluation of five patients with common variable immune deficiency (CVID) who have experienced SARS-CoV-2 virus. Here we assess the severity of the infection, the immunophenotypic profile of the major lymphocyte subgroups, the nonspecific T-cell functional capacity and the SARS-CoV-2 specific effector T-cell immune response. Our results showed that the course of COVID-19 infection in CVID patients was mild to moderate and none of them developed a critical form of the disease. All patients developed a specific SARS-CoV-2 T cell immune response. Lymphopenia as well as impaired T-cell response prior to COVID-19 appeared to be related to a more severe course of the infection. Data on a good specific T cell response against SARS-CoV-2 in CVID patients will help to make the right vaccination decision and establish its efficacy. Clinical outcome even in these individual cases was in agreement with the therapeutic recommendations underlining that regular maintenance with subcutaneous immunoglobulins can be beneficial against immune system overreaction and a severe disease course and convalescent plasma is a treatment option in patients with CVID and COVID-19.

Vasculitis as a Major Morbidity Factor in Patients With Partial RAG Deficiency.

Vasculitis can be a life-threatening complication associated with high mortality and morbidity among patients with primary immunodeficiencies (PIDs), including variants of severe and combined immunodeficiencies ((S)CID). Our understanding of vasculitis in partial defects in recombination activating gene (RAG) deficiency, a prototype of (S)CIDs, is limited with no published systematic evaluation of diagnostic and therapeutic modalities. In this report, we sought to establish the clinical, laboratory features, and treatment outcome of patients with vasculitis due to partial RAG deficiency. Vasculitis was a major complication in eight (13%) of 62 patients in our cohort with partial RAG deficiency with features of infections and immune dysregulation. Vasculitis occurred early in life, often as first sign of disease (50%) and was complicated by significant end organ damage. Viral infections often preceded the onset of predominately non-granulomatous-small vessel vasculitis. Autoantibodies against cytokines (IFN-α, -ω, and IL-12) were detected in a large fraction of the cases tested (80%), whereas the majority of patients were anti-neutrophil cytoplasmic antibodies (ANCA) negative (>80%). Genetic diagnosis of RAG deficiency was delayed up to 2 years from the onset of vasculitis. Clinical cases with sole skin manifestation responded well to first-line steroid treatment, whereas systemic vasculitis with severe end-organ complications required second-line immunosuppression and/or hematopoietic stem cell transplantation (HSCT) for definitive management. In conclusion, our data suggest that vasculitis in partial RAG deficiency is prevalent among patients with partial RAG deficiency and is associated with high morbidity. Therefore, partial RAG deficiency should be included in the differential diagnosis of patients with early-onset systemic vasculitis. Diagnostic serology may be misleading with ANCA negative findings, and search for conventional autoantibodies should be extended to include those targeting cytokines.

Chronic hepatitis C virus infection: prevalence of extrahepatic manifestations and association with cryoglobulinemia in Bulgarian patients.

AIM: To assess the prevalence of extrahepatic manifestations in Bulgarian patients with chronic hepatitis C virus (HCV) infection and identify the clinical and biological manifestations associated with cryoglobulinemia. METHODS: The medical records of 136 chronically infected HCV patients were reviewed to assess the prevalence of extrahepatic manifestations. Association between cryoglobulin-positivity and other manifestations were identified using chi2 and Fisher's exact test. Risk factors for the presence of extrahepatic manifestations were assessed by logistic regression analysis. RESULTS: Seventy six percent (104/136) of the patients had at least one extrahepatic manifestation. Clinical manifestations included fatigue (59.6%), kidney impairment (25.0%), type 2 diabetes (22.8%), paresthesia (19.9%), arthralgia (18.4%), palpable purpura (17.6%), lymphadenopathy (16.2%), pulmonary fibrosis (15.4%), thyroid dysfunction (14.7%), Raynaud's phenomenon (11.8%), B-cell lymphoma (8.8%), sicca syndrome (6.6%), and lichen planus (5.9%). The biological manifestations included cryoglobulin production (37.5%), thrombocytopenia (31.6%), and autoantibodies: anti-nuclear (18.4%), anti-smooth muscle (16.9%), anti-neutrophil cytoplasm (13.2%) and anti-cardiolipin (8.8%). All extrahepatic manifestations showed an association with cryoglobulin-positivity, with the exception of thyroid dysfunction, sicca syndrome, and lichen planus. Risks factors for the presence of extrahepatic manifestations (univariate analysis) were: age > or = 60 years, female gender, virus transmission by blood transfusions, longstanding infection (> or = 20 years), and extensive liver fibrosis. The most significant risks factors (multivariate analysis) were longstanding infection and extensive liver fibrosis. CONCLUSION: We observed a high prevalence of extrahepatic manifestations in patients with chronic HCV infection. Most of these manifestations were associated with impaired lymphoproliferation and cryoglobulin production. Longstanding infection and extensive liver fibrosis were significant risk factors for the presence of extrahepatic manifestations in HCV patients.