Test principle:The test principle applied in this kit is Sandwich enzyme immunoassay. The microtiter plate provided in this kit has been pre-coated with an antibody specific to Complement component 1, s subcomponent(C1S1). Standards or samples are added to the appropriate microtiter plate wells then with a biotin-conjugated antibody specific to Complement component 1, s subcomponent(C1S1). Next, Avidin conjugated to Horseradish Peroxidase (HRP) is added to each microplate well and incubated. After TMB substrate solution is added, only those wells that contain Complement component 1, s subcomponent(C1S1), biotin-conjugated antibody and enzyme-conjugated Avidin will exhibit a change in color. The enzyme-substrate reaction is terminated by the addition of sulphuric acid solution and the color change is measured spectrophotometrically at a wavelength of 450nm ± 10nm. The concentration of Complement component 1, s subcomponent(C1S1) in the samples is then determined by comparing the OD of the samples to the standard curve.