Interference is a generic term for effects leading to bad results. Interference leads to bad trueness, precision and reproducibility of immunoassays. There are many different kinds of interference. In many cases the decision, which kind of interference effect occurs, is not clear due to unknown molecular reasons for interference. Interference can be matrix effects, if the matrix is the source of the effect. It can be sample interference, if one or a few constituents of one sample generate the problem. Also cross-reactivities are a kind of interference, when the cross-reactant is known. Different kinds of interference are explained in the glossary.
Matrix effects are a kind of interference with an unknown cause. Matrix effects lead to poor accuracy of immunoassays. The molecular reason for the problem is not known, but the composition of the sample causes the interference. The transition to other interfering effects is fluent. Responsible for matrix effects are for example: Anti-animal antibodies, heterophilic antibodies, endogenous interfering substances or influence of viscosity, pH value or salt concentration. In some cases one can detect the molecular reason for such matrix effects. Then an effect, which was firstly described just as a matrix effect can be called a sample interference or a cross-reactivity, if the cross-reactant has been detected and described.