S100A8 and idiopathic pulmonary fibrosis: Among the myeloid/stromal innate immune mediators, IL-8, MIP-1α, IL-1α, S100A8/A9 levels were reduced in M-COV1/2 PBMCs (Figures 5A–D), compared to HC and IPF PBMCs (which overall behaved similarly), and there was always a trend for the last sequential sample (M-COV-3) behaving like HC or IPF samples (except for MIP-1a, whose levels remained low), again demonstrating a ‘return to homeostasis’ in these patients.