Ustekinumab Quantitation with Antibodies, Serum

Method Description

Ustekinumab (UTK) quantitation and anti-ustekinumab antibody measurements are performed using enzyme-linked immunosorbent assay. Microwell strips are pre-coated with UTK or anti-UTK antibody . Calibrators, controls, and patient samples are added to separate wells, allowing either UTK or antibodies to ustekinumab (ATUs) to bind to immobilized antigen. Unbound sample is washed away, and a second horseradish peroxidase-labeled anti-UTK or UTK (conjugate) is added to each well. A second incubation step allows the conjugate to bind to the UTK or ATU that has become attached to the microwells. After washing away the excess of unbound conjugate, the remaining enzyme activity is determined by adding a substrate and measuring the intensity of the color that develops in a spectrophotometer. The signal obtained is proportional to the amount of UTK or ATUs in the patient sample.