Complement
Definition
A group of heat-labile serum proteins (approximately 30 proteins, designated C1 through C9 in the classical pathway) that can be activated by immune complexes. When activated sequentially, they form a membrane attack complex that lyses target cells. In complement fixation tests, complement is supplied in a measured, limiting amount.
Related terms
- Complement fixation
- The binding and consumption of complement proteins by an antigen-antibody immune complex. Once fixed, complement is no longer available for the lytic...
- Conditional probability
- The probability of event A given that event B has already occurred, written P(A|B). Conditional probability is the basis of the multiplication...
- Cross-reactivity
- The capacity of an antibody raised against one analyte to bind structurally related compounds. In RIA, cross-reactivity is the main driver of...
- Event
- Any subset of the sample space to which a probability is assigned. An event may be a single outcome (this particular allele)...
- Independent events
- Two events where the occurrence of one provides no information about the other: P(A and B) = P(A) x P(B). In forensic...
- Indicator system
- In the complement fixation test, sheep red blood cells pre-coated with anti-sheep-RBC antibody (sensitised cells). These cells are lysed by free complement...
- Mutually exclusive events
- Two events that cannot both occur in the same trial. If a fibre is classified as cotton, it cannot simultaneously be classified...
- Postzone effect
- A false-negative serological result caused by antigen excess. When antigen greatly exceeds antibody, both binding sites on each antibody molecule are occupied...
- Prozone effect
- A false-negative serological result caused by antibody excess. When antibody concentration is too high relative to antigen, antibodies saturate individual antigen molecules...
- Sample space
- The set of all possible outcomes of an experiment. In forensic genetics, the sample space for a single allele call is the...
Explained in these topics
- Basic Probability RulesThe complement of event A is the event that A does not occur. Its probability is 1 - P(A). In court, practitioners frequently present the complement of a match...
- Complement Fixation and Mixed Antigen-Antibody ReactionsA group of heat-labile serum proteins (approximately 30 proteins, designated C1 through C9 in the classical pathway) that can be activated by immune complexes....