title: Iron compounds after erythrophagocytosis: chemical characterization and immunomodulatory effects.
abstract: In humans, the lymphomyeloid system has a fundamental role on iron metabolism promoting its recycling due to a continuous removal of effete red blood cells. Additionally, one of the most intriguing aspects of metalloporphyrins in biology is their effect on the immune system. However, the process of erythrocyte catabolism is still poorly understood and needs further research. In the present study, we attempt to investigate the nature and the possible physiologic role of Fe compounds released after erythrophagocytosis during the removal of red blood cells. Monocyte erythrophagocytosis in vitro experiments were done to characterize chemically the Fe compounds present inside the cells and in the culture supernatants. We tested the probable immunomodulatory functions of erythrophagocytosis products over lymphocyte cultures activated in vitro with T mitogens (alpha-CD3). Data obtained from atomic absorption spectroscopy confirmed the presence of Fe in the culture supernatants of monocyte cultures after erythrophagocytosis. Also, high-spin haem complexes derived from erythrocyte catabolism were detected by electron paramagnetic electronic resonance. Finally, in vitro activated lymphocyte proliferation experiments indicate the co-mitogenic properties of monocyte culture supernatants after red blood cells phagocytosis. Thus, the results of the present work provide evidence that culture monocyte supernatants after in vitro erythrophagocytosis contain Fe (III) high-spin haem complexes and show lymphocyte proliferation co-stimulatory properties.
authors.affiliation: Departamento de Imunologia e Patologia Molecular, Instituto de Ciências Biomédicas de Abel Salazar, Porto, Portugal.
authors.forename: L M
authors.initials: LM
authors.lastname: Costa
authors.forename: E M
authors.initials: EM
authors.lastname: Moura
authors.forename: J J
authors.initials: JJ
authors.lastname: Moura
authors.forename: M
authors.initials: M
authors.lastname: de Sousa
mesh_terms: D000276:Adjuvants, Immunologic / Q000097:blood / Q000737:chemistry / Q000502:physiology*; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D017252:CD3 Complex / Q000276:immunology; D002474:Cell-Free System / Q000276:immunology; D002478:Cells, Cultured; D004578:Electron Spin Resonance Spectroscopy; D004912:Erythrocytes / Q000737:chemistry* / Q000276:immunology; D006801:Humans; D007375:Interleukin-1 / Q000032:analysis / Q000502:physiology; D058085:Iron Compounds / Q000097:blood* / Q000737:chemistry* / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects / Q000276:immunology; D009000:Monocytes / Q000737:chemistry / Q000276:immunology; D010587:Phagocytosis; D013054:Spectrophotometry, Atomic; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis / Q000502:physiology
chemical_list: D000276:Adjuvants, Immunologic; D000911:Antibodies, Monoclonal; D017252:CD3 Complex; D007375:Interleukin-1; D058085:Iron Compounds; D014409:Tumor Necrosis Factor-alpha