Anti-SARS-CoV-2 IgG levels are associated with circulating levels of chemokines CXCL9/CXCL10 and severity disease, but not with RBD-specific B cells 4 months after COVID-19

Abstract Background: It has been reported that the humoral response and cytokine secretion is exacerbated in patients with severe COVID-19. However, it is unknown which cytokines are associated with the exacerbated humoral immune response during and after COVID-19. The aim of this study was to determine the association between cytokines and the humoral response of patients who had COVID-19 with different severity degree. Methods: 60 COVID-19 patients were recruited from Víctor-Rios-Ruiz Hospital during acute phase and at 4-months post-infection. Clinical exams were performed to evaluate lung damage after COVID-19. Serum samples were collected to measure IgG levels (Nucleocapsid + Spike) using commercial CLIA assays and cytokines and chemokines by Cytometric Bead Array (CBA). The percentage of B cell subsets and RBD-specific B cells were measured by flow cytometry. Results: Anti-SARS-CoV-2 IgG levels, but not RBD-specific B cells, were significantly associated with severity and pulmonary sequelae. Moreover, the data revealed that proinflammatory chemokines CXCL9 and CXCL10 were significantly correlated with Anti-SARS-CoV-2 IgG levels. We also observed that these chemokines promote CD40L upregulation and B cell differentiation into plasma cells. Conclusions: Severe COVID-19 patients produced higher anti-SARS-CoV-2 IgG levels than patients with mild disease, possibly due to an exacerbated immune response, associated with sustained levels of proinflammatory chemokines CXCL9 and CXCL10. This exacerbated response was associated with structural lung damage post-COVID-19. COVID1005 project Fondecyt Regular 1211480 ACT210085