Ultrastructural Modification of Anucleated Granulocytes in BALF

Granulocytes are commonly present in bronchoalveolar lavage fluid (BALF) along with other cell types. Under severe infection, the nuclei of blood granulocytes degrade, transforming them into anucleated granulocytes. Immunofluorescence (IF), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) have been used to analyze ultrastructural changes in anucleated granulocytes from the BALF of coronavirus disease 2019 (COVID-19) patients with and without comorbidities. Findings indicate that younger patients (≤60 y) exhibit higher severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infectivity but better preservation of intracellular structures compared to older patients (≥60 y). COVID-19 patients without comorbidities show a higher viral load than those with comorbidities. Among comorbid groups, diabetic patients experience the most severe ultrastructural damage in anucleated granulocytes. This chapter examines the ultrastructural changes in anucleated granulocytes within the BALF of COVID-19 patients across different age groups and comorbidity statuses.