title: HLA-DR expression in human fetal thymocytes.
abstract: We analyzed the expression of MHC class I (W6/32) and class II (HLA-DR) antigens on human fetal and postnatal thymocytes by fluorescence-activated cell sorting. Less than 5% of prenatal thymocytes expressed HLA-DR before week 12 of gestation. However, the number of HLA-DR-positive cells significantly increased during the late second and third trimester of gestation, when greater than 50% of prenatal thymocytes expressed HLA-DR. Such high-level expressions of HLA-DR in fetal thymocytes were also demonstrated by Northern-blot analysis and immunohistochemistry. After birth, the percentage of HLA-DR-positive cells in thymocytes decreased gradually. A high-level expression of class I antigen was also observed in thymocytes from the early stages of gestation, but, in contrast to MHC class II, a majority of postnatal thymocytes maintained high levels of class I antigen after birth.
authors.affiliation: Department of Pathology, College of Medicine, Seoul, South Korea.
authors.forename: S H
authors.initials: SH
authors.lastname: Park
authors.forename: Y M
authors.initials: YM
authors.lastname: Bae
authors.forename: T J
authors.initials: TJ
authors.lastname: Kim
authors.forename: I S
authors.initials: IS
authors.lastname: Ha
authors.forename: S
authors.initials: S
authors.lastname: Kim
authors.forename: J G
authors.initials: JG
authors.lastname: Chi
authors.forename: S K
authors.initials: SK
authors.lastname: Lee
mesh_terms: D002469:Cell Separation; D005314:Embryonic and Fetal Development / Q000276:immunology*; D005434:Flow Cytometry; D006684:HLA-DR Antigens / Q000032:analysis* / Q000235:genetics; D015395:Histocompatibility Antigens Class I / Q000032:analysis; D006801:Humans; D007150:Immunohistochemistry; D009693:Nucleic Acid Hybridization; D012333:RNA, Messenger / Q000032:analysis; D013601:T-Lymphocytes / Q000737:chemistry*; D013950:Thymus Gland / Q000166:cytology / Q000196:embryology / Q000276:immunology*
chemical_list: D006684:HLA-DR Antigens; D015395:Histocompatibility Antigens Class I; D012333:RNA, Messenger