Figure 1.

Overall workflow of BALF. Normal saline is injected into the alveolar cavity through the flexible bronchoscope, followed by negative pressure suction to recover the perfusate. The recollected fluid is BALF. After pretreatment and centrifugation, BALF is divided into two parts (cells and supernatant). Cells are used for cell smears, liquid-based cytology, and flow cytometry analysis. The supernatant can be subjected to ELISA, gene sequencing, or multi-omics analysis, such as proteomics, metabolomics, and microbiome analysis, allowing in-depth analysis of proteins, nucleic acids, metabolites, and the microbiome. (Created with BioRender.com).