title: Appearance of extrathymic early differentiated CD4-CD8- T cells with T cell receptor gamma/delta or alpha/beta after thymus grafting to nude mice: influence of thymus on extrathymic T cell differentiation.
abstract: Fetal thymus grafting into athymic nude mice has been used as an experimental model of T cell development. To understand the early events of T cell development, we have examined the sequence of appearance of T cell subsets in lymph nodes (LN) of BALB/c nu/nu mice after grafting with syngeneic fetal thymus. T cells expressing T cell receptor (TCR) alpha/beta or gamma/delta increased in LN from 1 week after grafting, although no host-derived CD3+ T cells were detected in the grafted thymus and no donor thymus-derived T cells were detected in the LN. The early appearing T cells of both TCR alpha/beta and TCR gamma/delta showed a CD4-CD8- phenotype. V region usage analysis of the early appearing TCR alpha/beta T cells revealed that they contained cells bearing V beta 3 or V beta 11, which are potentially reactive to self-superantigen Mls-2a or Dvb11, respectively, and are deleted in the course of T cell development in the thymus of euthymic BALB/c mice. The early appearing T cells showed neither mixed lymphocyte reaction nor cytotoxic T cell activity against allogeneic cells. In contrast, lymphokine-activated killer cells from early appearing T cells, which contained high percentages of TCR gamma/delta T cells, exhibited higher cytotoxic activity against P815 mastocytoma than those from euthymic mice or untreated nude mice. All these results suggest that the early appearing T cells are developed extrathymically. We propose that the thymus may induce extrathymic T cell development without direct cell-to-cell interaction. It seems likely that the extrathymically developed T cells, especially TCR gamma/delta T cells, induced by the thymus have some role in the defense mechanism in the absence of conventional thymus-derived T cells.
authors.affiliation: Department of Immunology, Kyushu University, Fukuoka, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Kenai
authors.forename: Y
authors.initials: Y
authors.lastname: Yoshikai
authors.forename: G
authors.initials: G
authors.lastname: Matsuzaki
authors.forename: A
authors.initials: A
authors.lastname: Iwasaki
authors.forename: H
authors.initials: H
authors.lastname: Yuuki
authors.forename: T
authors.initials: T
authors.lastname: Nakamura
authors.forename: K
authors.initials: K
authors.lastname: Nomoto
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D003602:Cytotoxicity, Immunologic; D005260:Female; D015979:Killer Cells, Lymphokine-Activated / Q000276:immunology; D007694:Killer Cells, Natural / Q000276:immunology; D008198:Lymph Nodes / Q000166:cytology; D008213:Lymphocyte Activation; D051379:Mice; D008806:Mice, Inbred AKR; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008819:Mice, Nude; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000378:metabolism; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000378:metabolism; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology*; D013950:Thymus Gland / Q000166:cytology* / Q000196:embryology / Q000637:transplantation
chemical_list: D016693:Receptors, Antigen, T-Cell, alpha-beta; D016692:Receptors, Antigen, T-Cell, gamma-delta