Functional maturation of mouse CD4+CD8- thymocytes induced by medullary-type thymus epithelial cells.
Murine CD4+CD8-(CD4SP) thymocyte subset is a heterogeneous population, in which the Qa-2- cells are less functional, whereas the Qa-2+ cells are fully functional. Evidence is provided here that the transition from Qa-2- to Qa-2+ CD4SP thymocytes is an intrathymic process of differentiation induced by thymic medullary-type epithelial cells. The separated Qa-2-CD4SP could be induced to express Qa-2 molecules up to 84%-89% of the total viable cells after cocultured for 3 d with MTEC1 cells, a murine thymic medullary type epithelial cell line established in our laboratory. Kinetic study showed that both the percentage of Qa-2+ cells and the density of the expressed Qa-2 molecules on CD4SP thymocytes induced by MTEC1 were progressively increasing in 72-h cultures. The MTEC1-induced Qa-2+CD4SP thymocytes were fully functional, which exhibited capabilities of proliferation and cytokine secretion in response to Con A stimulation as high as those of freshly isolated Qa-2+CD4SP thymocytes. The profile of cytokines secreted by MTEC1-induced Qa-2+CD4SP thymocytes was Thy 0 type specified by the production of IL-2, IL-4 and IL-6. The results suggest that Qa-2-CD4SP thymocytes may give rise to the Qa-2+CD4SP thymocytes, and acquire fully functional competence in thymic medulla under the foster of local epithelial cells.
Lu
L
L
Department of Immunology, Beijing Medical University, China.
Chen
W
W
D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D002478:Cells, Cultured; D018920:Coculture Techniques; D016207:Cytokines / Q000378:metabolism; D004847:Epithelial Cells / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000032:analysis; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology*
D016207:Cytokines; D016693:Receptors, Antigen, T-Cell, alpha-beta