In whole blood study, seven autoantigens were upregulated in blood of severe COVID-19 patients (MPO, PRTN3, PADI4, IFIH1, TRIM21, PTPRN2, and TSHR) (Figure 1B), while four autoantigens (MPO, PRTN3, IFIH1, and PADI4) were increased in blood of mild patients (Figure 1C). Here, PTPRN2 is linked to COVID-19.