IDO1 and pneumonia: Of interest, co-expression patterns discriminated cases with high viral loads (KLRG1, CTLA4, SP140, CD274, IDO1, LAG3, PDCD1, HAVCR2, and CD80) from samples with pneumonia (CD276, TGFB1, ADORA2A, LILRB4, LAIR1, VSIR, SIRPA, SIGLEC7, and SIGLEC9) suggesting a divergent pattern of induction of inhibitory immune-checkpoints during the course of covid-19 lung pathology (Figure 7G).