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Analysis of thymic subpopulations expressing the activation antigen GL7. Expression, genetics, and function
K S Hathcock1, C E Pucillo, G Laszlo
1Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
Journal of Immunology (Baltimore, Md. : 1950)
|November 15, 1995
Summary
The GL7 antibody identifies specific thymocyte populations in mice. These GL7-expressing cells, particularly CD4+CD8- adult thymocytes, exhibit distinct activation markers and cytokine secretion capabilities.
Area of Science:
- Immunology
- Cell Biology
- Developmental Biology
Background:
- The GL7 monoclonal antibody (mAb) identifies an activation antigen on stimulated B and T cells, and a subset of thymocytes.
- Previous work characterized GL7 expression on in vitro-stimulated cells and thymocytes.
Purpose of the Study:
- To analyze GL7-expressing populations in adult and fetal thymus.
- To characterize the phenotype and function of GL7+ thymocytes.
- To investigate genetic influences on GL7 expression levels.
Main Methods:
- Flow cytometry analysis of thymocyte populations using GL7 antibody and various cell surface markers (CD4, CD8, CD3, TCR, HSA, CD69).
- Analysis of thymocytes from different mouse strains (BALB/c, C57BL/6, CB6F1) to assess strain differences and genetic control of GL7 expression.
- Functional assays including TCR-specific stimulation to assess proliferation and cytokine (IL-4) secretion.
- Analysis of fetal thymocyte populations.
Main Results:
- The majority of GL7+ adult thymocytes are CD4+CD8- with high CD3 epsilon and TCR-alpha beta expression, low HSA, and bimodal CD69 expression.
- Significant strain differences in GL7 expression on adult CD4+CD8- thymocytes were observed, with BALB/c showing higher expression than C57BL/6, and low expression being dominant in F1 hybrids.
- CD4+CD8- GL7+ thymocytes from BALB/c mice, but not C57BL/6, showed a higher proportion of V beta 8+ cells.
- Adult GL7+ CD4+CD8- thymocytes are functionally competent, proliferating and secreting IL-4 upon TCR-specific stimulation.
- Fetal thymocytes contain GL7+ cells, predominantly CD4-CD8- with low HSA, CD69-, and bimodal TCR-gamma delta expression.
Conclusions:
- GL7 expression defines a subpopulation of functionally competent TCR-alpha beta+ CD4+CD8- adult thymocytes.
- GL7 also marks distinct TCR-gamma delta+ and TCR- subpopulations within fetal CD4-CD8- thymocytes.
- Genetic factors, potentially multiple genes, influence the level of GL7 expression on thymocytes.