title: Characterization of the subset of immature thymocytes which can undergo rapid in vitro differentiation.
abstract: Recently, we reported that thymocytes expressing the CD8 molecule on their surface can give rise to CD4+CD8+ double-positive and CD4+ single-positive progeny following intrathymic transfer into an irradiated host mouse. Thymcoytes expressing a high density of CD8, referred to as CD8hi, and those expressing a low density of the molecule, CD8lo, were both able to differentiate in vivo. In this study we examined the ability of these CD8+ thymocytes populations and of CD4-CD8- double-negative thymocytes to change their phenotype during brief in vitro culture. CD8+ thymocytes were prepared by anti-CD4 plus complement lysis followed by positive selection of the survivors on anti-CD8-coated plates. After 16 h of culture, greater than 60% of CD8+ thymocytes became double-positive. Both CD8hi and CD8lo cells were able to show this in vitro change: about 30% of the former and about 80% of the latter became double-positive. In contrast to this, double-negative thymocytes which had been depleted of cells expressing low densities of CD8 did not show such a phenotypic conversion in vitro. Further panning experiments suggested that all of the CD8+ thymocytes actually express a low surface density of the CD4 molecule which is undetectable in our cytofluorometric assays.
authors.affiliation: Department of Immunology, Research Institute of Scripps Clinic, La Jolla, CA 92037.
authors.forename: J
authors.initials: J
authors.lastname: Nikolić-Zugić
authors.forename: M W
authors.initials: MW
authors.lastname: Moore
authors.forename: M J
authors.initials: MJ
authors.lastname: Bevan
mesh_terms: D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology*; D016827:CD8 Antigens; D002454:Cell Differentiation; D002478:Cells, Cultured; D005434:Flow Cytometry; D066298:In Vitro Techniques; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D015375:Receptors, Interleukin-2 / Q000032:analysis; D013950:Thymus Gland / Q000166:cytology*
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D016827:CD8 Antigens; D015375:Receptors, Interleukin-2