title: The expression and sequences of T cell antigen receptor beta-chain genes in the thymus at an early stage after sublethal irradiation.
abstract: The sequential appearance of the thymocyte subpopulations and TCR gene messages occurred in the thymus of AKR mice (H-2k, Mlsa) from 7 to 14 days after sublethal irradiation. The thymocytes on day 7 after irradiation were composed of a large number of CD4+CD8+ blast-like cells and a relatively high proportion of CD4-CD8- cells (15 to 25%) but few CD3highCD4+CD8-/CD4-CD8+ cells. Approximately 22% of the CD4-CD8- cells were CD3high and -27% of the CD3highCD4-CD8- cells (-6% of whole CD4-CD8- cells) were F23.1+. The thymocytes on day 7 expressed a large amount of gamma- and delta-chain gene transcripts but reduced levels of alpha- and beta-chain gene transcripts. The V gene repertoire of 18 functional beta-chain cDNA derived from the thymocytes on day 7 was compared with those of 20 functional beta-chain cDNA derived from the thymocytes on day 14 which were composed of a large number of CD3lowCD4+CD8+ small-sized cells and a small number of CD3highCD4+CD8- cells. It is noteworthy that the distribution of V beta genes expressed in the thymocytes on day 7 was much the same as that in the thymocytes on day 14 but significantly different from that in normal BALB/c thymocytes as previously described. Interestingly, neither V beta 8.1 nor V beta 6 genes, which are important for recognition of the product of the Mlsa locus, was detected in these two cDNA libraries. These results suggest that clonal selection of TCR V beta repertoire, irrespective of positive or negative selection, appears to occur at the early stage of T cell differentiation, i.e., on the blast-like CD4+CD8+ thymocytes.
authors.affiliation: Department of Immunology, Kyushu University, Fukuoka, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Yuuki
authors.forename: Y
authors.initials: Y
authors.lastname: Yoshikai
authors.forename: K
authors.initials: K
authors.lastname: Kishihara
authors.forename: G
authors.initials: G
authors.lastname: Matsuzaki
authors.forename: K
authors.initials: K
authors.lastname: Ayukawa
authors.forename: K
authors.initials: K
authors.lastname: Nomoto
mesh_terms: D000595:Amino Acid Sequence / Q000528:radiation effects; D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis / Q000528:radiation effects; D001483:Base Sequence / Q000528:radiation effects; D002454:Cell Differentiation / Q000528:radiation effects; D004247:DNA / Q000302:isolation & purification; D005803:Genes, Immunoglobulin / Q000528:radiation effects*; D051379:Mice; D008806:Mice, Inbred AKR; D008969:Molecular Sequence Data; D010641:Phenotype; D011828:Radiation Chimera; D011948:Receptors, Antigen, T-Cell / Q000235:genetics* / Q000502:physiology / Q000528:radiation effects; D016693:Receptors, Antigen, T-Cell, alpha-beta; D013601:T-Lymphocytes / Q000378:metabolism* / Q000502:physiology / Q000528:radiation effects; D013950:Thymus Gland / Q000254:growth & development / Q000378:metabolism* / Q000528:radiation effects
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D011948:Receptors, Antigen, T-Cell; D016693:Receptors, Antigen, T-Cell, alpha-beta; D004247:DNA