CD55 and severe acute respiratory syndrome: On the other hand, DEGs in the PAMM1b subset mapped to GO terms associated with immune activation, cytokine production, and immune effector processes (Supplemental Figure 2E), with upregulation of ATF4, CD55, EREG, FCN1, THBS1, and MHC class I molecules (HLA-A, HLA-F) and downregulation of complement transcripts (C1QA, and C1QB) (Supplemental Figure 2F) in the maternal SARS+ group.