Proline-specific peptidase activities (DPP4, PRCP, FAP and PREP) in plasma of hospitalized COVID-19 patients.

"appendix a supplementary material the following are the supplementary data to this article: supplementary data 1 acknowledgements the authors thank marianne mangelschots sergio garcia charlotte drieghe niels lonneville and cindy van hoyweghen for their excellent technical assistance hanne van tiggelen the itm clinical trial unit and the uza/itm clinical team (involved in patient units d1 c3 a2 and icu 2-5) that helped in patient care recruitment and sampling."

"Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper."

"The authors thank Marianne Mangelschots, Sergio Garcia, Charlotte Drieghe, Niels Lonneville and Cindy Van Hoyweghen for their excellent technical assistance, Hanne Van Tiggelen, the ITM clinical trial unit and the UZA/ITM clinical team (involved in patient units D1, C3, A2 and ICU 2-5) that helped in patient care, recruitment and sampling. This work was financially supported by UAntwerp BOF/COVID grant 42809."

"This study is a post-hoc analysis within the COVID-19 Immune Repertoire Sequencing (IMSEQ) study, a prospective cohort study conducted at the Antwerp University Hospital (UZA). The study design is described separately (clinical trials.gov NCT04368143). The research complied with all the relevant national regulations, institutional policies and in accordance with the tenets of the Helsinki Declaration, and was approved by the University Hospital Antwerp/University of Antwerp ethics committee (Belgian registration number: 20/12/135) and the ITM IRB. All individuals gave their written informed consent."