[Cell-associated complement regulatory proteins and their relation to disease processes]
1Department of Immunology, Center for Adult Diseases, Osaka.
Insights
The complement system
Area of Science:
- Immunology
- Biochemistry
Background:
- Complement system activation is crucial for eliminating foreign materials.
- Self cells express complement regulatory proteins to avoid C3 attack.
Purpose of the Study:
- To review the properties of complement regulatory proteins.
- To discuss the link between diseases and aberrant regulatory proteins.
Main Methods:
- Literature review of complement system functions.
- Analysis of complement regulatory proteins (CR1, DAF, MCP).
Main Results:
- C3 deposition initiates complement activation.
- CR1, DAF, and MCP protect self cells from complement-mediated damage.
- Aberrant regulatory proteins are linked to disease processes.
Conclusions:
- Complement regulatory proteins are essential for self-tolerance.
- Dysregulation of these proteins contributes to various diseases.
Abstract:
C3-deposition is a key step for activation of the complement system, which involves C9-mediated immunocytolysis, immunoadherence, C3 receptor-mediated phagocytosis, NK potentiation, anaphylatoxin release, and amplification of C3 activation. Foreign material is eliminated even in the preimmune stage by these complement functions. Self cells, on the other hand, must circumvent the C3-attack, so that they express complement regulatory proteins, namely C3b/C4b receptor (CR1, CD35), decay-accelerating factor (DAF, CD55), membrane cofactor protein (MCP, CD46). We herein review the properties of these regulatory proteins and discuss the relationships between disease processes and the aberrance of these regulatory proteins.
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