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Characterization of decay-accelerating factor (DAF) in human skin
K Sayama1, S Shiraishi, Y Shirakata
1Department of Dermatology, University of Ehime School of Medicine, Japan.
The Journal of Investigative Dermatology
|January 1, 1991
Summary
Decay-accelerating factor (DAF) is found in human epidermis, with its epidermal form differing in sialic acid content and anchoring mechanism compared to blood cells. This suggests a unique role for DAF in skin.
Area of Science:
- Immunology
- Dermatology
- Biochemistry
Background:
- Decay-accelerating factor (DAF) is a 70-kD glycoprotein regulating complement activation.
- DAF has a broad tissue distribution and prevents complement convertase assembly.
Purpose of the Study:
- To investigate the presence and characteristics of DAF in normal human epidermis.
- To elucidate the anchoring mechanism of DAF in epidermal cells and on elastic fibers.
Main Methods:
- Immunohistochemistry using monoclonal antibodies against DAF.
- Western blot analysis of DAF from epidermal and buffy coat cells.
- Enzymatic treatment with neuraminidase and phosphatidylinositol-specific phospholipase C (PIPLC).
Main Results:
- DAF antigen was detected in the intercellular spaces of normal human epidermis, with higher concentrations in the granular layer.
- Epidermal DAF showed a lower molecular weight (55 kD) than buffy coat DAF (67 kD), with differences in sialic acid content.
- PIPLC treatment released epidermal DAF, indicating PI-mediated anchoring to keratinocytes, while DAF on elastic fibers was not PI-anchored.
Conclusions:
- DAF is present in the human epidermis, with distinct biochemical properties compared to DAF in blood cells.
- Epidermal DAF is anchored to keratinocytes via phosphatidylinositol (PI).
- DAF on elastic fibers utilizes a different, non-PI-mediated anchoring mechanism.