Comprehensive evaluation of bronchoalveolar lavage from patients with severe COVID-19 and correlation with clinical outcomes

• Published in: Human pathology Vol. 113; pp. 92 - 103
• Main Authors: Gelarden, Ian, Nguyen, Jessica, Gao, Juehua, Chen, Qing, Morales-Nebreda, Luisa, Wunderink, Richard, Li, Lin, Chmiel, Joan S., Hrisinko, MaryAnn, Marszalek, Laura, Momnani, Sumaiya, Patel, Pinal, Sumugod, Ricardo, Chao, Qi, Jennings, Lawrence J., Zembower, Teresa R., Ji, Peng, Chen, Yi-Hua
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.07.2021; Elsevier Limited; The Author(s). Published by Elsevier Inc
• Subjects: Adult; Aged; Aged, 80 and over; Atypical lymphocyte; Bronchoalveolar lavage; Bronchoalveolar Lavage Fluid - cytology; Bronchoalveolar Lavage Fluid - immunology; CD4-Positive T-Lymphocytes - immunology; CD8-Positive T-Lymphocytes - immunology; Clinical outcome; Coronaviruses; COVID-19; COVID-19 - immunology; Female; Humans; Lung - immunology; Lymphocytes; Male; Middle Aged; Mortality; Original Contribution; SARS-CoV-2; United States > US; COVID-19; Clinical outcome; SARS-CoV-2; Bronchoalveolar lavage; Atypical lymphocyte
• ISSN: 0046-8177; 1532-8392
• DOI: 10.1016/j.humpath.2021.04.010

Information on bronchoalveolar lavage (BAL) in patients with COVID-19 is limited, and clinical correlation has not been reported. This study investigated the key features of BAL fluids from COVID-19 patients and assessed their clinical significance. A total of 320 BAL samples from 83 COVID-19 patients and 70 non-COVID-19 patients (27 patients with other respiratory viral infections) were evaluated, including cell count/differential, morphology, flow cytometric immunophenotyping, and immunohistochemistry. The findings were correlated with clinical outcomes. Compared to non-COVID-19 patients, BAL from COVID-19 patients was characterized by significant lymphocytosis (p < 0.001), in contrast to peripheral blood lymphopenia commonly observed in COVID-19 patients and the presence of atypical lymphocytes with plasmacytoid/plasmablastic features (p < 0.001). Flow cytometry and immunohistochemistry demonstrated that BAL lymphocytes, including plasmacytoid and plasmablastic cells, were composed predominantly of T cells with a mixture of CD4+ and CD8+ cells. Both populations had increased expression of T-cell activation markers, suggesting important roles of helper and cytotoxic T-cells in the immune response to SARS-CoV-2 infection in the lung. More importantly, BAL lymphocytosis was significantly associated with longer hospital stay (p < 0.05) and longer requirement for mechanical ventilation (p < 0.05), whereas the median atypical (activated) lymphocyte count was associated with shorter hospital stay (p < 0.05), shorter time on mechanical ventilation (p < 0.05) and improved survival. Our results indicate that BAL cellular analysis and morphologic findings provide additional important information for diagnostic and prognostic work-up, and potential new therapeutic strategies for patients with severe COVID-19.