SPP1 and infection: As anticipated previously, BALFs of SARS-CoV-2-affected patients show higher proportions of monocytes, macrophages, and neutrophils than healthy controls, expressing ficolin-1 (FCN1) and secreted phosphoprotein 1 (SPP1) markers and immunoregulatory genes [72], while fatty acid binding protein 4-expressing macrophages are preferentially contained in BALFs from patients with mild infection and healthy controls and completely lost in severely infected patients [72].