EndoS inhibits metabolic oxygen responses induced by RBCs sensitized with anti-D immune plasma. Metabolic oxygen responses from monocytes were analyzed by measuring the chemiluminescence after addition of RBC-sensitized anti-D-positive plasma (with or without treatment with EndoS) and luminol, at 5-minute intervals for 1 hour. y-axis represents opsonic index, ie, the ratio of monocyte responses to sensitized RBCs versus unsensitized RBCs. control RBC indicates RBCs sensitized with nonimmune plasma.