Interplay of antibody and cytokine production reveals CXCL-13 as a potential novel biomarker of lethal SARS-CoV-2 infection

The SARS-CoV-2 pandemic is continuing to impact the global population. This study was designed to assess the interplay of antibodies with the systemic cytokine response in SARS-CoV-2 patients. We demonstrate that significant anti-SARS-CoV-2 antibody production to Receptor Binding Domain (RBD), Nucleocapsid (N), and Spike S1 subunit (S1) of SARS-CoV-2 develops over the first 10 to 20 days of infection. The majority of patients produced antibodies against all three antigens (219/255 SARS-CoV-2 positive patient specimens, 86%) suggesting a broad response to viral proteins. Patient mortality, sex, blood type, and age were all associated with differences in antibody production to SARS-CoV-2 antigens which may help explain variation in immunity between these populations. To better understand the systemic immune response, we analyzed the production of 20 cytokines by SARS-CoV-2 patients over the course of infection. Cytokine analysis of SARS-CoV-2 positive patients exhibited increases in proinflammatory markers (IL-6, IL-8, IL-18) and chemotactic markers (IP-10, SDF-1, MIP-1 β , MCP-1, and eotaxin) relative to healthy individuals. Patients who succumbed to infection produced decreased IL-2, IL-4, IL-12, IL-13, RANTES, TNF-α, GRO-α, and MIP-1α relative to patients who survived infection. We also observed that the chemokine CXCL13 was particularly elevated in patients that succumbed to infection. CXCL13 is involved in B cell activation, germinal center development, and antibody maturation, and we observed that CXCL13 levels in blood trended with anti-SARS-CoV-2 antibody production. Furthermore, patients that succumbed to infection produced high CXCL13 and also tended to have high ratio of nucleocapsid to RBD antibodies. This study provides insights into SARS-CoV-2 immunity implicating the magnitude and specificity of response in relation to patient outcomes. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This project was supported by the Vaccine Development Center at the West Virginia University Health Sciences Center. FHD and the VDC are supported by the Research Challenge Grant no. HEPC.dsr.18.6 from the Division of Science and Research, WV Higher Education Policy Commission. Funding for generating antigens was provided by the WVU Health Science Center Office of Research and Graduate Education. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Oversight by: WVU IRB and WVU Office of Human Research Protections IRB #:2004976401 All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All data in this manuscript is provided in associated supplementary files.