Complement Dependent Killing
Complement Dependent Killing - Related Videos
04:29
Assessment of Opsonophagocytic Killing Activity against Bacterial Pathogens
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2025
The video shows an in vitro opsonophagocytic killing assay using a co-culture of human neutrophils with Streptococcus pneumoniae. Antibodies and complement proteins facilitate opsonization of the bacteria, enabling neutrophils to recognize and kill bacteria, showing successful neutrophil opsonophagocytic activity.
06:17
Depletion of Specific Cell Populations by Complement Depletion
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Cited by 15 •
2010
To effectively study the function of immune cell populations their purification is often required. Complement depletion is a fast and inexpensive technique for the isolation of immune cell populations with high purity.
01:27
Complement System
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2024
The complement system is a group of approximately 20 plasma proteins that strengthen the body's defenses against infections through opsonization, inflammation, and cell lysis. Opsonization involves coating pathogens with complement proteins, making them more recognizable and facilitating phagocyte engulfment. Certain complement proteins induce inflammation that attracts immune cells to the site of infection. Cell lysis involves the destruction of pathogens through the formation of a membrane...
00:49
Complementation Tests
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2021
A complementation test is a simple cross to identify whether the two mutations are located on the same gene or different genes. It was first performed by Edward Lewis in the 1940s while working on fruit flies. He developed the test to identify the location and arrangement of different mutations on chromosomes. Organisms heterozygous for different mutations are crossed pairwise in all combinations. If present on different genes, the mutations can complement each other by providing the missing...
04:29
Bimolecular Complementation Affinity Purification to Isolate Two Interacting Proteins
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2025
In this video, we have demonstrated bimolecular complementation affinity purification, BiCAP, to detect and isolate specific protein dimers using conformation-specific single-domain antibodies.
FAQs
The classical pathway links recognition to membrane damage through an ordered proteolytic cascade. Antibodies attached to a microbial surface initiate complement activation; downstream cleavage events promote C3b deposition and can culminate in membrane attack complex assembly. This sequence connects target recognition with both tagging for cellular uptake and direct injury.
C3b and the membrane attack complex contribute in distinct ways. C3b acts as an opsonin, marking the microbial surface for more effective interaction with phagocytic defenses. The membrane attack complex instead forms pores in susceptible membranes, which can damage or lyse the target. Together, these outcomes support complementary routes of pathogen control.
The outcome depends partly on whether a target membrane is susceptible to damage by membrane attack complex pores. This helps explain why complement activation does not produce identical effects against every microbe. Comparing resistant and susceptible targets can also reveal bacterial evasion strategies that limit complement-mediated injury or reduce the effectiveness of host defense.
Complement-dependent killing functions as part of a broader immune response rather than as an isolated event. C3b deposition supports opsonization and therefore complements phagocytic clearance, while complement activity also contributes to inflammation. Direct membrane injury, enhanced uptake, and inflammatory responses can operate together to improve control of invading bacteria.
A useful conceptual sequence begins with antibody attachment to the microbial surface, followed by classical-pathway activation and proteolytic amplification. Researchers can then examine C3b deposition, membrane attack complex formation, target-cell damage, and the relationship to phagocytosis and inflammation. Tracking these linked outcomes helps distinguish direct lysis from broader immune cooperation.
The process provides a framework for understanding how antibody-based therapies may contribute to microbial control. Researchers can consider whether therapeutic antibodies promote classical-pathway activation, C3b deposition, or membrane attack complex formation against susceptible targets. These effects help connect antibody binding with potential direct pathogen damage and cooperation with other immune defenses.