Induction of T-cell differentiation.
T cell development can be viewed as precursor cells migrating from yolk-sac and liver in the embryo, and bone marrow and spleen in the adult to the thymic cortex as functionally immature T-cells, and to the medulla where they acquire immunological function, and finally joining the pool of T-cells in the blood lymphoid system and spleen. Several cell surface markers were used to study these processes, such as TL, Ly-1, Ly-2/3, Qa-1, and I-J. Using these cell surface markers combined with biologically active reagents in functional tests in vitro, several conclusions can be drawn to illustrate these differentiation steps. 1) T cell precursors are precommitted and can be separated from other hematopoietic stem cells. 2) During induction of prothymocytes several new unlinked gene products are expressed. 3) Thymopoietin is a physiological inducer. 4) This induction to express new surface markers requires transcription and translation but is independent of DNA synthesis, at least according to the action of metabolic inhibitors. 5) Surface phenotypes and function of cells are coordinately programmed. 6) Most Ly1 and Ly23 cells, if not all, are derived from Ly123 precursor cells. 7) Acquisition of new surface phenotype precedes new functional expression, supporting the hypothesis that the differentiation process consists in pre-mitotic expression of a gene set for phenotype, and postmitotic expression of a set for function. 8) The differentiation steps require cell-cell interaction, either by direct contact or by soluble factors within the same T-cell linkage.
D000818:Animals; D000954:Antigens, Surface / Q000032:analysis; D002450:Cell Communication; D002454:Cell Differentiation; D002868:Chromosomal Proteins, Non-Histone / Q000494:pharmacology; D006801:Humans; D007114:Immunization; D010641:Phenotype; D013601:T-Lymphocytes / Q000166:cytology*; D013934:Thymectomy; D014158:Transcription, Genetic; D014452:Ubiquitins
D000954:Antigens, Surface; D002868:Chromosomal Proteins, Non-Histone; D014452:Ubiquitins