EndoS inhibits secretion of IL-8 by monocytes induced by RBCs sensitized with anti-D. Relative quantification of IL-8 secretion in supernatants from THP-1 cells or blood monocytes incubated with RBCs sensitized with anti-D for 3 hours, with or without pretreatment of anti-D with EndoS. (Inset) IL-8 incubated with EndoS followed by separation on SDS-PAGE and staining with Coomassie Blue.