title: Macrophages are involved in DNA degradation of apoptotic cells in murine thymus after administration of hydrocortisone.
abstract: In the present study, we undertook kinetic analyses of DNA degradation and acid DNase activity in murine thymus after administration of hydrocortisone. Hydrocortisone induced apoptosis in thymocytes, and a large number of cortical thymocytes became TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP biotin nick end labelling)-positive (TUNEL+). F4/80+ macrophages infiltrated through the cortico-medullay junction into the cortical region, and thereafter engulfed apoptotic cells in the cortex of thymus. The distribution of acid DNase-active cells appeared to be similar to that of F4/80+ macrophages. Eighteen hours after the injection, although the foci of apoptotic cells were situated within massively distended F4/80+ macrophages, oligonucleosomal DNA fragments on an agarose gel were undetectable. Our results showed that macrophages were involved in the disappearance of oligonucleosomal DNA fragments in apoptotic thymocytes. Taken together, macrophages play a role in the hydrolysis of DNA in apoptotic cells upon their phagocytosis of the dead cells.
authors.affiliation: Department of Bacterial and Blood Products, National Institute of Infectious Diseases, Tokyo, 162-8640, Japan.
authors.forename: C
authors.initials: C
authors.lastname: Odaka
authors.forename: T
authors.initials: T
authors.lastname: Mizuochi
mesh_terms: D000818:Animals; D017209:Apoptosis; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D053938:DNA Fragmentation; D003851:Deoxyribonucleases / Q000032:analysis; D005260:Female; D006854:Hydrocortisone / Q000008:administration & dosage / Q000494:pharmacology*; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D007267:Injections; D007700:Kinetics; D008212:Lymphocyte Depletion; D008264:Macrophages / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008954:Models, Biological; D009707:Nucleosomes / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology; D013950:Thymus Gland / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology / Q000648:ultrastructure
chemical_list: D009707:Nucleosomes; D004247:DNA; D003851:Deoxyribonucleases; D006854:Hydrocortisone