title: Early separation of B and T lymphocyte precursors in chick embryo.
abstract: Embryonic chimeras were used to demonstrate an early separation of chicken T and B cell precursors. Genetically polymorphic cell surface antigens, Bu-1 and Ov, which are expressed on cells of the B and T lineage, respectively, are useful markers in adoptive cell transfer studies. Allelic products Bu-1a and Bu-1b can be detected with monoclonal antibodies (mAbs) L22 and 11G2, respectively, and the Ov antigen with mAb 11A9. Chimeric chickens were constructed by reconstituting irradiated 14-d Ov- H.B19 embryos with the sorted Bu-1+ or Bu-1- fractions of spleen cells from age-matched H.B19 Ov+ embryos. Chimeras were analyzed, 3-4 wk after hatching, for the presence of Ov+ cells in the bursa, thymus, spleen, and peripheral blood lymphocytes. T cell precursors giving rise to thymocytes and peripheral T cells were present only in the Bu-1-, but not in the Bu-1+, fraction. We previously demonstrated that, in contrast, all B cell precursors in spleen from 14-d embryos are exclusively present in the Bu-1+ fraction. We also analyzed the immunoglobulin light chain gene rearrangement in these populations by polymerase chain reaction. We show here that VJ recombination occurs in the Bu-1+, but not in the Bu-1-, fraction of spleen. These data demonstrate an early commitment to the B cell lineage, which occurs before the colonization of the bursa of Fabricius. Segregation of B cell precursors from the other hemopoietic precursors, and consequently separation of T and B cell precursors, occurs before the colonization of the primary lymphoid organs.
authors.affiliation: Faculté des Sciences, Université de Nantes, France.
authors.forename: E
authors.initials: E
authors.lastname: Houssaint
authors.forename: A
authors.initials: A
authors.lastname: Mansikka
authors.forename: O
authors.initials: O
authors.lastname: Vainio
mesh_terms: D000483:Alleles; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000954:Antigens, Surface / Q000276:immunology; D001402:B-Lymphocytes / Q000166:cytology* / Q000276:immunology; D001483:Base Sequence; D002454:Cell Differentiation; D002642:Chick Embryo; D002645:Chickens; D002678:Chimera; D004247:DNA / Q000032:analysis; D005455:Fluorescent Antibody Technique; D015328:Gene Rearrangement, B-Lymphocyte, Light Chain / Q000276:immunology; D007124:Immunoenzyme Techniques; D008221:Lymphoid Tissue / Q000166:cytology; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D016133:Polymerase Chain Reaction; D013234:Stem Cells / Q000166:cytology; D013601:T-Lymphocytes / Q000166:cytology* / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D015345:Oligonucleotide Probes; D004247:DNA