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Deposition of C3 on bacteria in the mouse uterus after mating
1Department of Anatomy, School of Medicine, Southern Illinois University, Carbondale 62901-6503.
Abstract:
A previous study demonstrated that several species of bacteria were present in the mouse uterine lumen on the day after mating, and that many of these bacteria had immunoglobulins bound to their surface. Neutrophilic leukocytes containing phagocytosed bacteria were also present in the lumen. Since bacteria are phagocytosed efficiently only when they are opsonized by the binding of specific antibody or C3b or both to their surface, we investigated whether the uterine bacteria were coated with C3. Immunolabeling demonstrated that an antigenic portion of C3, possibly C3b, was bound to many of the uterine bacteria. This observation suggests that bacteria in the mouse uterus after mating may be opsonized by both antibody and complement and that phagocytosis of these bacteria by neutrophils may play an important role in returning the uterus to an aseptic state before implantation.
Insights
Bacteria in the mouse uterus after mating are coated with complement protein C3 and immunoglobulins. This opsonization facilitates neutrophil phagocytosis, aiding in maintaining a sterile uterus before implantation.
Area of Science:
- Reproductive immunology
- Microbiology
- Immunology
Background:
- Bacteria are detected in the mouse uterine lumen post-mating.
- These bacteria often have immunoglobulins on their surface.
- Neutrophils containing phagocytosed bacteria are present in the uterine lumen.
Purpose of the Study:
- To investigate if complement protein C3 opsonizes uterine bacteria.
- To understand the role of complement in bacterial clearance post-mating.
Main Methods:
- Immunolabeling techniques were used.
- Detection of C3 and its fragments (like C3b) on uterine bacteria.
Main Results:
- An antigenic portion of C3, likely C3b, was found bound to many uterine bacteria.
- Evidence suggests bacteria are opsonized by both antibodies and complement.
Conclusions:
- Complement opsonization of uterine bacteria occurs post-mating.
- Phagocytosis by neutrophils, enhanced by opsonization, is crucial for uterine sterilization before implantation.