What is meant by complement system?
The complement system, also known as complement cascade, is a part of the immune system that enhances (complements) the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism, promote inflammation, and attack the pathogen’s cell membrane.
How does a complement system work?
The complement system is made up of a large number of distinct plasma proteins that react with one another to opsonize pathogens and induce a series of inflammatory responses that help to fight infection. A number of complement proteins are proteases that are themselves activated by proteolytic cleavage.
How do you memorize complements?
Mnemonic for Complement system:
- Classical pathway: Complex (Immune complex) activated; C1 + C4 – C2 = C3.
- Mannose binding lectin (MBL) pathway: Microbe mannose activated.
- Alternative pathway: Alien particles (like microbe or tumor cells) activated; Factors mediated.
What are the effects of the complement system?
Complement can opsonize bacteria for enhanced phagocytosis; it can recruit and activate various cells including polymorphonuclear cells (PMNs) and macrophages; it can participate in regulation of antibody responses and it can aid in the clearance of immune complexes and apoptotic cells.
What are examples of Opsonins?
Examples of opsonin molecules include:
- antibodies: IgG and IgA.
- components of the complement system: C3b, C4b, and iC3b.
- Surfactant.
- Mannose-binding lectin (initiates the formation of C3b)
What are the 3 functions of the complement system?
At the basic level the broad functions of the complement system can be split into three areas: (1) the activation of inflammation; (2) the opsonization (labeling) of pathogens and cells for clearance/destruction; (3) the direct killing of target cells/microbes by lysis.
How important is the complement system?
Complement has essential importance in some physiological processes: In the induction of the humoral immune response, in the elimination of immune complexes and in the protection against bacterial and viral infections.
Is IgM an opsonin?
Phagocytic cells do not have an Fc receptor for immunoglobulin M (IgM), making IgM ineffective in assisting phagocytosis alone. However, IgM is extremely efficient at activating complement and is, therefore, considered an opsonin.
What is the difference between opsonins and cytokines?
The key difference between cytokines and opsonins is that cytokines are small extracellular proteins that participate in cell signalling, while opsonins are large extracellular proteins that bind to cells and induce phagocytosis. Based on these messages, the neighbouring cells generate responses.
