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Human complement regulator expression by the normal female reproductive tract
T J Oglesby1, J E Longwith, P C Huettner
1Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Insights
Complement regulators like membrane cofactor protein (MCP) and decay-accelerating factor (DAF) show distinct expression patterns in the female reproductive tract, suggesting non-complement roles.
Area of Science:
- Immunology
- Reproductive Biology
- Cellular Biology
Background:
- Membrane-associated proteins regulate complement activation, protecting cells from damage.
- Key regulators include membrane cofactor protein (MCP; CD46), decay-accelerating factor (DAF; CD55), and CD59.
- These proteins have recognized roles in reproductive, tumor, and transplantation immunology, with potential non-complement functions.
Purpose of the Study:
- To compare the expression of complement regulators in the human female reproductive tract.
- To detail the distribution of MCP, DAF, and CD59 in normal ovaries, fallopian tubes, cervices, and uterine corpi.
Main Methods:
- Immunohistochemical analysis of normal female reproductive tissues.
- Utilized well-characterized monoclonal antibodies for precise detection.
- Compared expression patterns of key complement regulators across different tissues and cell types.
Main Results:
- Membrane cofactor protein (MCP) showed diffuse, strong expression on epithelia and endothelium, and was predominant on oocytes.
- Decay-accelerating factor (DAF) exhibited variable epithelial expression and was absent on some epithelia and oocytes.
- CD59 was widely present on epithelia, vascular tissue, and stroma, with varying staining intensity.
Conclusions:
- Complement regulator expression in the female reproductive tract follows distinct, reproducible patterns.
- Differential expression, particularly on oocytes, suggests potential non-complement functions.
- This study provides a foundation for investigating pathological tissues and cellular localization mechanisms.
Background:
The membrane-associated proteins that regulate human complement activation are ubiquitously expressed and function cooperatively to protect cells from autologous complement damage. For classical and alternative pathways, the primary regulators at the stage of C3 proteolysis and deposition are membrane cofactor protein (MCP; CD46) and decay-accelerating factor (DAF;CD55), whereas protectin or CD59 regulates terminal component assembly. There is increasing awareness in reproductive, tumor, and transplantation immunology of the conventional and non-complement roles of these proteins. The human reproductive system may serve as a model of the non-complement functions.
Methods:
We performed immunohistochemical analyses of multiple normal ovaries, fallopian tubes, cervices, and uterine corpi by using well-characterized monoclonal antibodies to provide a detailed, direct comparison of complement regulator expression.
Results:
Membrane cofactor protein was diffusely and strongly expressed on all epithelia and vascular endothelium and was the predominant regulator on oocytes. In contrast, decay-accelerating factor had variable expression in intensity and distribution on epithelia and was notably absent on certain epithelia and oocytes. It was the only regulator present on the connective tissue between muscle bundles in the myometrium and the cervix and was found on most stroma. CD59, although staining intensity varied, was present on virtually all epithelia, vascular tissue, and stroma.
Conclusions:
Distinct reproducible patterns of complement regulator expression are found throughout the female reproductive tract. Differential expression on certain epithelia and oocytes may suggest non-complement activities. This comprehensive study should provide a basis for further characterization of pathological tissues and mechanisms of cellular localization.