Restricted onset of T cell receptor alpha gene rearrangement in fetal and neonatal thymocytes.
The initial T cell receptor (TCR) alpha gene rearrangements were analyzed in fetal and neonatal thymocyte hybridomas by Southern blotting. Interestingly, in 30% of all thymocyte hybridomas and in all fetal day 16 thymocyte hybridomas the most proximal J alpha 50 (psi J alpha) gene was rearranged. This rearrangement was found on one chromosome only and mostly in association with a delta rearrangement on the homologous chromosome. J alpha 50 was rearranged to multiple target genes based on the variable size of the restriction fragments. In addition, delta rearrangement was found with a concomitant alpha rearrangement in the majority of hybridomas and it was not only associated with J alpha 50 but with several other rearranged J alpha genes as well. Our results clearly demonstrate that T cell precursors are not pre-committed to either delta or alpha rearrangement but a flexible progenitor responds to multiple regulatory signals during T cell differentiation and they do not support the notion that delta rec-psi J alpha rearrangement is required for cell commitment to TCR alpha gene rearrangement.
Rytkönen
M A
MA
Department of Clinical Microbiology, University of Kuopio, Finland. Marja.Rytkonen@uku.fi
Hurwitz
J L
JL
Thompson
S D
SD
Pelkonen
J
J
D000818:Animals; D000831:Animals, Newborn / Q000235:genetics / Q000276:immunology*; D005314:Embryonic and Fetal Development / Q000235:genetics / Q000276:immunology*; D005260:Female; D015329:Gene Rearrangement, T-Lymphocyte; D006825:Hybridomas / Q000378:metabolism; D007133:Immunoglobulin Joining Region / Q000235:genetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics*; D013601:T-Lymphocytes / Q000378:metabolism*; D013950:Thymus Gland / Q000196:embryology / Q000276:immunology
D007133:Immunoglobulin Joining Region; D016693:Receptors, Antigen, T-Cell, alpha-beta