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Expression of the Fas ligand in cells of T cell lineage
Abstract:
Fas ligand (FasL) is a membrane-type cytokine belonging to the TNF family, and induces apoptosis through its cell-surface receptor, Fas. To determine the cell types that express FasL, various mouse tissues and cell lines were examined by Northern hybridization using a mouse FasL cDNA as a probe. Among tissues, lymphoid organs (thymus, lymph node, spleen), lung, and small intestine express low levels of FasL mRNA, suggesting the role of FasL in the general immune system and mucosal immunity. The testis expressed FasL mRNA most abundantly; however, the size of FasL mRNA in the testis was slightly shorter than those in other tissues. Distribution of FasL mRNA in a panel of cell lines indicated that the FasL expression is rather restricted to the cells of T cell lineage. Activation of the splenocytes with the T cell activators such as PMA and ionomycin, Con A, anti-CD3, or even IL-2 alone induced the expression of the FasL. CD8+ splenocytes expressed the FasL more abundantly than did the CD4+ splenocytes upon activation by Con A and IL-2. Among CD4+ CTL cell lines, the FasL was expressed in all Th1 and Th0, and some Th2 clones.
Insights
Fas ligand (FasL) is expressed in various mouse tissues, notably the testis and lymphoid organs. T cell activation significantly upregulates FasL, with CD8+ T cells showing higher expression than CD4+ cells.
Area of Science:
- Immunology
- Molecular Biology
Background:
- Fas ligand (FasL) is a TNF family cytokine that induces apoptosis via the Fas receptor.
- Understanding FasL expression is crucial for dissecting immune responses and cell death pathways.
Purpose of the Study:
- To identify the specific cell types and tissues expressing FasL mRNA in mice.
- To investigate the regulation of FasL expression in T lymphocytes.
Main Methods:
- Northern hybridization using a mouse FasL cDNA probe.
- Analysis of FasL mRNA expression in various mouse tissues and cell lines.
- Examination of FasL expression in activated splenocytes and T cell subsets.
Main Results:
- FasL mRNA was detected in lymphoid organs, lung, and small intestine, with highest abundance in the testis (notably shorter transcript).
- FasL expression was primarily restricted to T cell lineage cells.
- Activation of splenocytes with various stimuli (PMA/ionomycin, Con A, anti-CD3, IL-2) induced FasL expression.
- CD8+ splenocytes showed higher FasL induction than CD4+ splenocytes.
- Th1, Th0, and some Th2 CD4+ CTL clones expressed FasL.
Conclusions:
- FasL plays a role in general immunity and mucosal immunity.
- T cell activation, particularly in CD8+ T cells, is a key regulator of FasL expression.
- FasL expression patterns suggest distinct roles in different immune cell subsets and tissues.