title: MHC class II beta-chain and alphaIIbbeta3 integrin are expressed on T-cell progenitors in embryonic bone marrow.
abstract: The RR5 monoclonal antibody (mAb) was obtained after immunization of mice with hemopoietic cells from chicken embryos. The cDNA encoding the protein recognized by RR5 was cloned using COS-7 cells transfected with an embryonic bone marrow (BM) cDNA library. The epitope recognized by the RR5 mAb was located on the non-polymorphic MHC class II beta-chain molecule. In the embryonic BM, RR5 labeled 50% of the c-kit expressing cells. Previous experiments have shown that the T-cell progenitors are present in the MHC class II(+)/c-kit(+) BM population along with myeloid progenitors and that T-cell and myeloid progenitors also express the integrin alphaIIbbeta3. In this study, using intrathymic cell transfer experiments in chicks, we have tested the T-cell differentiation potential of MHC class II/alphaIIbbeta3 double positive cells. It proved to be similar to that of the c-kit/MHC class II positive cells. However, injection of triple positive cells resulted in a selection of cells with an increased T-cell potential. Most of the MHC class II positive cells which do not express c-kit are prone to apoptosis, indicating that these progenitors might need a survival signal via c-kit. Interestingly, the MHC class II positive progenitors lose this expression after intrathymic transfer. Taken together our data suggest that the presence of the MHC class II beta-chain molecule on the surface of BM progenitor cells could be implicated in differentiation toward myeloid and lymphoid lineages.
authors.affiliation: Département de Pathologie, Centre Médical Universitaire (CMU), Geneva, Switzerland. christiane.ody@medecine.unige.ch
authors.forename: C
authors.initials: C
authors.lastname: Ody
authors.forename: C
authors.initials: C
authors.lastname: Corbel
authors.forename: D
authors.initials: D
authors.lastname: Dunon
authors.forename: O
authors.initials: O
authors.lastname: Vainio
authors.forename: B
authors.initials: B
authors.lastname: A  Imhof
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001854:Bone Marrow Cells / Q000276:immunology*; D019556:COS Cells; D002642:Chick Embryo; D002522:Chlorocebus aethiops; D018985:Epitopes, B-Lymphocyte / Q000276:immunology; D015870:Gene Expression; D006412:Hematopoietic Stem Cells / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000235:genetics*; D011110:Polymorphism, Genetic; D019009:Proto-Oncogene Proteins c-kit; D012333:RNA, Messenger; D013601:T-Lymphocytes / Q000276:immunology*; D013950:Thymus Gland
chemical_list: D018985:Epitopes, B-Lymphocyte; D000949:Histocompatibility Antigens Class II; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D012333:RNA, Messenger; D019009:Proto-Oncogene Proteins c-kit