Erythrocyte lysis by monocytes: investigations on the mechanism and role of the target cell hydrogen peroxide catabolizing pathways.
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.
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
D009895:Opsonin Proteins; D006997:Hypochlorous Acid; D015054:Zymosan; D006861:Hydrogen Peroxide