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Murine epidermal cell-derived thymocyte-activating factor resembles murine interleukin 1
Journal of Immunology (Baltimore, Md. : 1950)
|May 1, 1982
Summary
Epidermal cell-derived thymocyte-activating factor (ETAF) shares characteristics with interleukin 1 (IL 1). Injurious stimuli increase ETAF production, suggesting a close relationship or identity between ETAF and IL 1.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Epidermal cell-derived thymocyte-activating factor (ETAF) is produced by keratinocytes.
- ETAF exhibits biological and biochemical similarities to macrophage-derived interleukin 1 (IL 1).
- Both ETAF and IL 1 are polypeptides with similar molecular weight and stability characteristics.
Purpose of the Study:
- To develop a quantitative microassay for standardized assessment of ETAF activity.
- To further define the characteristics of ETAF.
- To elucidate the relationship between ETAF and IL 1.
Main Methods:
- Quantitative microassay for ETAF activity.
- Stimulation of keratinocytes with lipopolysaccharide (LPS) or silica.
- Assessment of thymocyte proliferation and response to ETAF and IL 1.
Main Results:
- Keratinocyte production of ETAF activity increased with LPS, silica, mechanical disruption, and hydroxyurea treatment.
- ETAF shares an isoelectric point of 5.2 with murine IL 1.
- Specific thymocyte subpopulations (PNA- Lyt-2-) responded to ETAF, similar to IL 1.
- ETAF demonstrated mitogenic activity for fibroblasts.
Conclusions:
- ETAF production is influenced by "injurious" stimuli that prolong the G1 phase of the cell cycle.
- The findings strongly support the hypothesis that ETAF is identical or closely related to IL 1.
- ETAF functions as a mitogenic signal for fibroblasts, mirroring IL 1 activity.