title: Thymic nurse cells exhibit epithelial progenitor phenotype and create unique extra-cytoplasmic membrane space for thymocyte selection.
abstract: Thymic nurse cells (TNCs) are epithelial cells in the thymic cortex that contain as many as 50 thymocytes within specialized cytoplasmic vacuoles. The function of this cell-in-cell interaction has created controversy since their discovery in 1980. Further, some skepticism exists about the idea that apoptotic thymocytes within the TNC complex result from negative selection, a process believed to occur exclusively within the medulla. In this report, we have microscopic evidence that defines a unique membranous environment wherein lipid raft aggregates around the alphabetaTCR expressed on captured thymocytes and class II MHC molecules expressed on TNCs. Further, immunohistological examination of thymic sections show TNCs located within the cortico-medullary junction to express cytokeratins five and eight (K5 and K8), and the transcription factor Trp-63, the phenotype defined elsewhere as the thymic epithelial progenitor subset. Our results suggest that the microenvironment provided by TNCs plays an important role in thymocyte selection as well as the potential for TNCs to be involved in the maintenance of thymic epithelia.
authors.affiliation: Department of Biology, The City College of New York, New York, 10031, USA.
authors.forename: Tonya M
authors.initials: TM
authors.lastname: Hendrix
authors.forename: Rajendra V E
authors.initials: RV
authors.lastname: Chilukuri
authors.forename: Marcia
authors.initials: M
authors.lastname: Martinez
authors.forename: Zachariah
authors.initials: Z
authors.lastname: Olushoga
authors.forename: Andrew
authors.initials: A
authors.lastname: Blake
authors.forename: Moazzam
authors.initials: M
authors.lastname: Brohi
authors.forename: Christopher
authors.initials: C
authors.lastname: Walker
authors.forename: Michael
authors.initials: M
authors.lastname: Samms
authors.forename: Jerry C
authors.initials: JC
authors.lastname: Guyden
mesh_terms: D000818:Animals; D002450:Cell Communication / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D004847:Epithelial Cells / Q000502:physiology* / Q000648:ultrastructure; D042541:Intracellular Space / Q000378:metabolism; D007633:Keratins / Q000378:metabolism; D008285:Major Histocompatibility Complex; D051379:Mice; D008810:Mice, Inbred C57BL; D010641:Phenotype; D013234:Stem Cells / Q000502:physiology* / Q000648:ultrastructure; D013950:Thymus Gland / Q000166:cytology*
chemical_list: D007633:Keratins