Cross-linking of the T cell antigen receptor interferes with the generation of CD4+8+ thymocytes from their immediate CD4-8+ precursors.
The majority of thymocytes are immature cells co-expressing the surface markers CD4 and CD8. About two thirds of these cells also express the T cell antigen receptor (TcR), though at a level distinctly lower than found on mature T cells. The direct precursors of these "double-positive" thymocytes are cycling cortical blast cells of the CD4-8+ phenotype. Using a new monoclonal antibody to a constant determinant of the rat TcR alpha/beta, it is shown here that (a) about 50% of these CD8 "single-positive" committed precursor cells already express the TcR alpha/beta, though at very low levels, (b) during short-term suspension culture in medium supplemented only with fetal calf serum they not only acquire CD4 but also TcR alpha/beta levels characteristic of CD4,8 "double-positive" thymocytes, and (c) cross-linking of the TcR during culture inhibits the acquisition of the CD4 antigen in the majority of these cells.
Hünig
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Genzentrum der Ludwig-Maximilians-Universität München, Martinsried, FRG.
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology; D016827:CD8 Antigens; D002454:Cell Differentiation; D002478:Cells, Cultured; D003432:Cross-Linking Reagents; D005260:Female; D005434:Flow Cytometry; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011948:Receptors, Antigen, T-Cell / Q000502:physiology*; D013601:T-Lymphocytes / Q000166:cytology* / Q000276:immunology
D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D016827:CD8 Antigens; D003432:Cross-Linking Reagents; D011948:Receptors, Antigen, T-Cell