Complement fixation refers to: Group of answer choices the ingestion of C3b-coated bacteria by macrophages the destruction of complement in serum heating at 56C for 30 minutes the covalent binding of complement components to a pathogen's surface the interaction of C3b with Mast cells
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Complement fixation is a process in the immune response where complement proteins bind to pathogens, marking them for destruction. Show more…
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Proteins 1. Complement is a system of plasma that circulates in the blood in an inactive form. Complement is activated when it becomes attached to the surface of foreign cells (bacteria, fungi, red blood cells). The result of this complement fixation is that some of the complement elements, called the complement proteins, become inserted in the membrane of the foreign cell. This forms a complex which causes lysis of the foreign cell. Some of the chemicals released during complement fixation enhance phagocytosis. This is called opsonization. Others amplify the inflammatory response.
Madhur L.
When complement proteins are covalently deposited onto the surface of a bacterium, this can sometimes lead to direct lysis of the bacterium. However, more commonly, the deposition of complement proteins onto the bacterial surface does not directly harm the bacterium. Instead, these complement proteins aid in bacterial elimination by: a) Recruiting antibodies to the bacterial surface, leading the antibody-dependent neutralization b) Cross-linking carbohydrate structures on the bacterial surface, thereby preventing the bacterium from replicating c) Stimulating B lymphocytes to produce more antibodies against the bacterium d) Providing a mechanism for phagocytes bearing complement receptors to recognize and ingest the bacterium e) Providing a mechanism for phagocytes to use their Fc receptors to recognize and ingest the bacterium
During an immune response, host damage from complement is generally limited to the area in which complement is activated. Which are properties of complement proteins that contribute to this observation? Select ALL that apply. Activated complement proteins generally have short half-lives, which favors a rapid inactivation state. Regulatory proteins, such as decay-accelerating factor (DAF), rapidly degrade complement components. Complement protein, C3b, activates opsonization by phagocytic cells. Complement proteins, C3a and C5a, induce anaphylaxis. The membrane attack complex (MAC) is inserted into membranes composed of lipid bilayers.
Adi S.
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