SARS-CoV-2 antibodies, serum inflammatory biomarkers and clinical severity of hospitalized COVID-19 Patients

Gozalbo-Rovira, R.; Gimenez, E.; Latorre, V.; Frances-Gomez, C.; Albert, E.; Buesa, J.; Marina, A.; Blasco, M. L.; Signes-Costa, J.; Rodriguez-Diaz, J.; Geller, R.; Navarro, D.

Background: The involvement of SARS-CoV-2 antibodies in mediating immunopathogenetic events in COVID-19 patients has been suggested. By using several experimental approaches, we investigated the potential association between SARS-CoV-2 IgGs recognizing the spike (S) protein receptor-binding domain (RBD), neutralizing antibodies (NtAb) targeting S, and COVID-19 severity. Patients and Methods: This unicenter, retrospective, observational study included 51 hospitalized patients (24 at the intensive care unit; ICU). A total of 93 sera from these patients collected at different time points from the onset of symptoms were analyzed. SARS-CoV-2 RBD IgGs were quantitated by ELISA and NtAb50 titers were measured in a GFP reporter-based pseudotyped virus platform. Demographic and clinical data, complete blood counts, as well as serum levels of ferritin, Dimer-D, C reactive protein (CRP), lactose dehydrogenase (LDH), and interleukin-6 (IL-6) were retrieved from clinical charts. Results: The overall correlation between levels of both antibody measurements was good (Rho=0.79; P=0<0.001). SARS-CoV-2 RBD IgG and NtAb50 levels in sera collected up to day 30 after the onset of symptoms were comparable between ICU and non-ICU patients (P=>0.1). The percentage of patients who exhibited high NtAb50 titers ([≥]160) was similar (P=0.20) in ICU (79%) and non-ICU (60%) patients. Four ICU patients died; two of these achieved NtAb50 titers [≥]1/160 while the other two exhibited a 1/80 titer. Very weak (Rho=>0.0-<0.2) or weak (Rho=>0.2-<0.4) correlations were observed between anti-RBD IgGs, NtAb50, and serum levels pro-inflammatory biomarkers. Conclusions: The data presented herein do not support an association between SARS-CoV-2 RBD IgG or NtAb50 levels and COVID-19 severity