LAUSR

Abstract Objectives Being COVID-19 convalescent plasma (CCP) a therapeutic option that can have a potential impact on the normalization of immunological parameters of COVID-19 affected patients, a detailed analysis of post-infusion immunological changes was conducted in CCP treated patients, aiming to identify possible predictive hallmarks of disease prognosis. Methods This prospective observational study describes a cohort of 28 patients who received CCP shortly after being hospitalized for COVID-19 and diagnosed for Acute Respiratory Distress Syndrome. All patients were subjected to a detailed flow cytometry based evaluation of immunological markers at baseline and on days +3 and +7 after transfusion. Results At baseline almost all patients suffered from lymphopenia (25/28 on T-cells and 16/28 on B-cells) coupled with neutrophil-lymphocyte ratio exceeding normal values (26/28). Lymphocyte subsets were generally characterized by increased percentages of CD19+CD20-CD38hiCD27+ plasmablasts and reduction of CD4+CD45RA+CCR7+CD31+ recent thymic emigrants, while monocytes presented a limited expression of CD4 and HLA-DR molecules. Amelioration of immunological parameters began to be evident from day +3 and became more significant at day +7 post-CCP transfusion in 18 patients who recovered within 30 days from hospitalization. Conversely, baseline immunological characteristics generally persisted in ten critical patients who eventually progressed to death (6) or long-term care (4). Conclusions This study demonstrates that proper immunophenotyping panels can be potentially useful for monitoring CCP treated patients from the first days after infusion in order to presume higher risk of medical complications.