CD4 and COVID-19: The findings indicated that the high expression of CASP1 in COVID-19 may induce this disease by “tyrosine metabolism,” “base excision repair,” and “glyoxylate and dicarboxylate metabolism,” while down-regulation of CASP1 promoted “DORSO_VENTRAL_AXIS_FORMATION,” “O_GLYCAN_BIOSYNTHESIS,” and “VALINE_LEUCINE_AND_ISOLEEUCINE_BIOSYNTHESIS.” CD4, whose expression was limited in COVID-19 samples, was significantly correlated with the immune response (“AUTOIMMUNE THYROID DISEASE,” “GRAFT VERSUS HOST DISEASE,” and “ALLOGRAFT REJECTION”).