(B) IL-5. levels of cytokines, chemokines, NETs and AC antibodies 3 months after recruitment according to the development of a sustained humoral immune response. The serum levels of the cytokines, chemokines, NETs and the titers of AC antibodies are expressed as medians and interquartile ranges and were compared with the Wilcoxon test. DataSheet_1.docx (1.6M) GUID:?2184E4FB-5C05-4D9C-98B3-86A1AC7E003D Supplementary Table?3: Comparison of the serum levels of cytokines, chemokines and AC antibodies in patients with COVID-19, 6 months after recruitment according to the diagnosis of a sustained humoral immune response. The serum levels of Sirt4 the cytokines and chemokines are expressed as medians and interquartile ranges and were compared with the Wilcoxon test. DataSheet_1.docx (1.6M) GUID:?2184E4FB-5C05-4D9C-98B3-86A1AC7E003D Supplementary Table?4: Univariate logistic regression analysis of the statistically significant features associated to the development of a sustained humoral immune response in patients with COVID-19. DataSheet_1.docx (1.6M) GUID:?2184E4FB-5C05-4D9C-98B3-86A1AC7E003D Supplementary Table?5: Repeated-measures analysis of the differential Batimastat sodium salt serum levels of cytokines 6 months after recruitment considering the disease severity and the development of Batimastat sodium salt a sustained humoral immune response. DataSheet_1.docx (1.6M) GUID:?2184E4FB-5C05-4D9C-98B3-86A1AC7E003D Data Availability StatementThe original contributions presented in the study are included in the article/ Supplementary Material . Further inquiries can be directed to the corresponding authors. Abstract Background Until now, most of the research addressing long-term humoral responses in coronavirus disease 2019 (COVID-19) had only evaluated the serum titers of anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgGs, without the assessment of the baseline antiviral clinical and immune profile, which is the aim of this study and may be the key factor leading to a broad and sustained antibody response. Methods We included 103 patients with COVID-19. When the patients sought medical attention (baseline), a blood sample was drawn to perform immunophenotype of lymphocytes by flow cytometry. The patients were assessed 15 days after baseline and then every month until the third month, followed by a last visit 6 months after recruitment. We evaluated the anti-SARS-COV-2 IgG at all time points, and the serum levels of cytokines, chemokines, anti-cellular (AC) antibodies and neutrophil extracellular traps were also assessed during the follow-up. The primary outcome of the study was the presence of a sustained immune humoral response, defined as an anti-SARS-CoV-2 IgG titer >4.99 arbitrary units/mL in at least two consecutive measures. We used generalized lineal models to assess the features associated with this outcome and to assess the effect of the changes in the cytokines and chemokines throughout time around the development of a sustained humoral immune response. Results At baseline the features associated to a sustained immune humoral response were the diagnosis of critical disease, absolute number of lymphocytes, serum IP-10, IL-4, IL-2, regulatory T cells, CD8+ T cells, and positive AC antibodies. Critical illness and the positivity of AC antibodies were associated with a sustained humoral immune response after 3 months, whilst critical illness and serum IL-13 were the explanatory variables after 6 months. Conclusion A sustained immune humoral response is usually strongly related to critical COVID-19, which is characterized by the presence of AC antibodies, quantitative abnormalities in the T cell compartment, and the serum cytokines and chemokines during acute contamination and throughout time. Keywords: SARS-CoV-2, humoral response, COVID-19, lymphopenia, anti-cellular antibodies Introduction Severe acute respiratory syndrome (SARS-CoV-2) has affected 78 million individuals and is responsible for over 1.7 million deaths to date (1). After its emergence, initial scientific efforts were focused on the understanding of the acute antiviral immune response (2), but currently, the long-term cellular and humoral immune responses against SARS-CoV-2 have become relevant (3). In this regard, there is an increased interest in the detection of a sustained humoral immune response as a marker of anti-SARS-CoV-2 vaccination, as well as a key risk factor for re-infection (3, 4), and for the development of post-coronavirus disease 2019 (COVID-19) syndrome (5). Nearly all patients with COVID-19 develop a humoral antiviral immune response (6). The magnitude of the humoral immune response is strongly correlated with the disease severity (7) and the duration of active contamination (8), highlighting the importance of the initial antiviral response in the development of sustained humoral immunity. A prolonged and severe COVID-19 is the clinical consequence of a disturbed adaptive and innate antiviral immune response. In this regard, patients with COVID-19 are characterized by the expression of PD1 and CD57 in the T cell compartment, which has been related to an enhanced production of TNF, CD107a, IFN-, IL-2 and Batimastat sodium salt IL-17 (9). Many pro-inflammatory.