title: Thymotaxin: a thymic epithelial peptide chemotactic for T-cell precursors.
abstract: The embryonic thymus is seeded by invading hemopoietic precursor cells that differentiate intrathymically into T lymphocytes. We have recently reported that avian thymic epithelial cells secrete chemotactic peptides, which provoke oriented migration of hemopoietic precursor cells in vitro. The established rat thymic epithelial cell line IT-45 R1 produced a polypeptide that resolves as a single band in the region of 11 kDa on NaDodSO4/polyacrylamide gels. This molecule, which we have named thymotaxin, induced a chemotactic response in a subpopulation of hemopoietic cells from juvenile rat bone marrow. Responding cells were generated by short-term coculture of rat bone marrow hemopoietic cells with mouse bone marrow stroma in a steroid-free medium. Cells selected in a chemotactic chamber have a lymphoid or blast cell morphology. The phenotype of the responding cells is Thy-1+, CD4- [corrected] and CD8-. In contrast, CD8 T-lymphocyte differentiation antigen was expressed after coculture with embryonic thymic monolayers, suggesting that the responding cells correspond to the precursors colonizing the thymus.
mesh_terms: D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte; D001854:Bone Marrow Cells; D002454:Cell Differentiation; D002460:Cell Line; D002478:Cells, Cultured; D002630:Chemotactic Factors / Q000096:biosynthesis / Q000276:immunology*; D002634:Chemotaxis, Leukocyte; D004847:Epithelial Cells; D004848:Epithelium / Q000276:immunology; D006412:Hematopoietic Stem Cells / Q000276:immunology*; D007375:Interleukin-1 / Q000276:immunology; D008297:Male; D051379:Mice; D051381:Rats; D011919:Rats, Inbred Strains; D013601:T-Lymphocytes / Q000276:immunology*; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology*; D001613:beta 2-Microglobulin
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D002630:Chemotactic Factors; D007375:Interleukin-1; D001613:beta 2-Microglobulin