title: Erythrocyte lysis by monocytes: investigations on the mechanism and role of the target cell hydrogen peroxide catabolizing pathways.
abstract: The erythrocyte (RBC) lysis by human monocytes incubated with opsonized zymosan particles (OPZ), was inhibited by catalase, chloride-free medium, azide and hypochlorous acid (HOCl) scavengers (taurine, alanine). These findings suggest the requirement for the HOCl-generating myeloperoxidase-hydrogen peroxide-chloride system (MPO-H2O2-Cl- system). The HOCl-dependent lysis was increased by inhibiting RBC catalase with aminotriazole (AT). Conversely, the inhibition of RBC glutathione cycle with 1,3-bis (2-chloroethyl)-1-nitrosourea (BCNU) had no detectable effect. Moreover, the recovery of H2O2 and HOCl from OPZ-triggered monocytes was reduced by the presence of RBCs through a process almost completely preventable by pulsing RBCs with AT but not with BCNU. Thus, it appears that RBC targets protect themselves by consuming, primarily via catalase, significant amounts of monocyte-derived H2O2 with a consequent impairment of the HOCl generation. The results suggest a potential role of target cells in modulating the cytolysin production by monocytes.
mesh_terms: D004912:Erythrocytes / Q000276:immunology* / Q000378:metabolism; D006461:Hemolysis; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D006997:Hypochlorous Acid / Q000378:metabolism; D008297:Male; D009000:Monocytes / Q000276:immunology*; D009895:Opsonin Proteins / Q000276:immunology; D015054:Zymosan / Q000276:immunology
chemical_list: D009895:Opsonin Proteins; D006997:Hypochlorous Acid; D015054:Zymosan; D006861:Hydrogen Peroxide