T cell receptor targeting to thymic cortical epithelial cells in vivo induces survival, activation and differentiation of immature thymocytes.
We report that targeting of T cell receptors (TcR) to non-major histocompatibility complex (MHC) molecules on thymic cortical epithelial cells by hybrid antibodies in vivo and in fetal thymic organ cultures results in phenotypic and functional differentiation of thymocytes. A single pulse with hybrid antibodies rescues immature, CD4/8 double-positive thymocytes from their programmed death in vivo, induces expression of the early activation antigen CD69 followed by TcR up-regulation, concomitant down-regulation of CD8 or CD4 and their conversion to functional mature T cells by day 3. This temporal sequence of maturation only affects small thymocytes without co-induction of blastogenesis. TcR targeting to MHC class II-positive epithelial cells predominantly induces CD4-positive T cells. This generation of CD4 single-positive T cells occurs also in MHC class II-deficient mice and thus is independent of CD4-MHC class II interactions. Moreover, in the presence of a specific deleting antigen (Mls 1a), TcR targeting results in transient activation of immature thymocytes, however, not in subsequent TcR (V beta 6) up-regulation and development of single-positive T cells. Our findings imply that TcR cross-linking to cortical epithelial cells is sufficient to confer a differentiation signal to immature thymocytes. Furthermore, this approach distinguishes two independent TcR-mediated intrathymic events: activation and subsequent deletion of the same thymocyte subset.
Müller
K P
KP
Tumor Immunology Programme, German Cancer Research Center, Heidelberg.
Kyewski
B A
BA
D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology; D002454:Cell Differentiation; D002470:Cell Survival; D004848:Epithelium / Q000276:immunology; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D008213:Lymphocyte Activation; D051379:Mice; D008815:Mice, Inbred Strains; D011993:Recombinant Fusion Proteins; D013601:T-Lymphocytes / Q000166:cytology*; D013950:Thymus Gland / Q000166:cytology*
D000911:Antibodies, Monoclonal; D000949:Histocompatibility Antigens Class II; D011993:Recombinant Fusion Proteins