To determine events that transpire during the earliest stages of human T cell development, we have studied fetal tissues before (7 wk), during (8.2 wk), and after (9.5 wk to birth) colonization of the fetal thymic rudiment with hematopoietic stem cells. Calculation of the approximate volumes of the 7- and 8.2-wk thymuses revealed a 35-fold increase in thymic volumes during this time, with 7-wk thymus height of 160 microM and volume of 0.008 mm3, and 8.2-wk thymus height of 1044 microM and volume of 0.296 mm3. Human thymocytes in the 8.2-wk thymus were CD4+ CD8 alpha+ and cytoplasmic CD3 epsilon+ cCD3 delta+ CD8 beta- and CD3 zetta-. Only 5% of 8-wk thymocytes were T cell receptor (TCR)-beta+, < 0.1% were TCR-gamma+, and none reacted with monoclonal antibodies against TCR-delta. During the first 16 wk of gestation, we observed developmentally regulated expression of CD2 and CD8 beta (appearing at 9.5 wk), CD1a,b, and c molecules (CD1b, then CD1c, then CD1a), TCR molecules (TCR-beta, then TCR-delta), CD45RA and CD45RO isoforms, CD28 (10 wk), CD3 zeta (12-13 wk), and CD6 (12,75 wk). Whereas CD2 was not expressed at the time of initiation of thymic lymphopoiesis, a second CD58 ligand, CD48, was expressed at 8.2 wk, suggesting a role for CD48 early in thymic development. Taken together, these data define sequential phenotypic and morphologic changes that occur in human thymus coincident with thymus colonization by hematopoietic stem cells and provide insight into the molecules that are involved in the earliest stages of human T cell development.
Skip Nav Destination
Article navigation
1 April 1995
Article|
April 01 1995
Early human T cell development: analysis of the human thymus at the time of initial entry of hematopoietic stem cells into the fetal thymic microenvironment.
B F Haynes,
B F Haynes
Department of Medicine, Duke University School of Medicine, Durham, North Carolina 27710, USA.
Search for other works by this author on:
C S Heinly
C S Heinly
Department of Medicine, Duke University School of Medicine, Durham, North Carolina 27710, USA.
Search for other works by this author on:
B F Haynes
Department of Medicine, Duke University School of Medicine, Durham, North Carolina 27710, USA.
C S Heinly
Department of Medicine, Duke University School of Medicine, Durham, North Carolina 27710, USA.
Online ISSN: 1540-9538
Print ISSN: 0022-1007
J Exp Med (1995) 181 (4): 1445–1458.
Citation
B F Haynes, C S Heinly; Early human T cell development: analysis of the human thymus at the time of initial entry of hematopoietic stem cells into the fetal thymic microenvironment.. J Exp Med 1 April 1995; 181 (4): 1445–1458. doi: https://doi.org/10.1084/jem.181.4.1445
Download citation file:
Sign in
Don't already have an account? Register
Client Account
You could not be signed in. Please check your email address / username and password and try again.
Could not validate captcha. Please try again.
Sign in via your Institution
Sign in via your InstitutionSuggested Content
Email alerts
Advertisement