title: MHC class II engagement inhibits CD99-induced apoptosis and up-regulation of T cell receptor and MHC molecules in human thymocytes and T cell line.
abstract: Major histocompatibility complex (MHC) class II surface levels on thymocytes increase after CD99 ligation. The functional implication of the up-regulated MHC class II was assessed by engaging MHC class II on CD99-ligated cells. MHC class II engagement down-modulated surface levels of T cell receptor and MHC molecules, and inhibited apoptosis of CD99-ligated thymocytes and CEM tumor cells, antagonistic effects on the previously reported CD99 functions. The results were reproducible regardless of the order of ligation of MHC class II and CD99. We suggest that signaling via MHC class II on CD99-engaged cells might be involved in the thymic maturation process by damping CD99 ligation effects.
authors.affiliation: Department of Pathology, College of Medicine, Seoul National University, Yongun-dong 28, Chongro-gu, Seoul 110-799, South Korea.
authors.forename: Min Kyung
authors.initials: MK
authors.lastname: Kim
authors.forename: Yoon-La
authors.initials: YL
authors.lastname: Choi
authors.forename: Min Kyung
authors.initials: MK
authors.lastname: Kim
authors.forename: Seok-Hyung
authors.initials: SH
authors.lastname: Kim
authors.forename: Eun Young
authors.initials: EY
authors.lastname: Choi
authors.forename: Won Seo
authors.initials: WS
authors.lastname: Park
authors.forename: Young Mee
authors.initials: YM
authors.lastname: Bae
authors.forename: Sang Kyu
authors.initials: SK
authors.lastname: Woo
authors.forename: Seong Hoe
authors.initials: SH
authors.lastname: Park
mesh_terms: D000071443:12E7 Antigen; D015703:Antigens, CD / Q000502:physiology*; D017209:Apoptosis / Q000502:physiology*; D015815:Cell Adhesion Molecules / Q000502:physiology*; D002460:Cell Line; D015536:Down-Regulation; D005434:Flow Cytometry; D000949:Histocompatibility Antigens Class II / Q000502:physiology*; D006801:Humans; D011948:Receptors, Antigen, T-Cell / Q000502:physiology*; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology*; D015854:Up-Regulation
chemical_list: D000071443:12E7 Antigen; D015703:Antigens, CD; C061828:CD99 protein, human; D015815:Cell Adhesion Molecules; D000949:Histocompatibility Antigens Class II; D011948:Receptors, Antigen, T-Cell