In an ELISA procedure, what is the purpose of washing the plate after incubating with the patient sample?

Washing the plate after incubating with the patient sample in an ELISA procedure is essential for ensuring the accuracy and reliability of the results. The primary purpose of this wash step is to remove unbound substances, which include excess antibodies, antigens, or other reactants that may not have specifically bound to the target. This is crucial because any unbound materials left on the plate can lead to background noise in the signal, making it difficult to accurately quantify the amount of the target analyte present. By washing, the assay ensures that only those components that have formed a specific complex remain, facilitating a clear distinction between positive and negative results.

The washing process also minimizes the chances of false positives, as any remaining unbound substances could react non-specifically and interfere with the detection mechanism. Thus, this step is vital for enhancing the specificity of the assay and ensuring that the results reflect true binding events rather than artefactual signals.