Analyte detection immunoassay

A system comprising reagents for performing an immunoassay for the detection of a target analyte comprising:

• (a) a surface displaying capture agents that the target analyte is capable of stably binding;
• (b) a luciferase-labeled competitor capable of binding to the capture agents;
• (c) a luciferase-labeled detection agent comprising the same luciferase label as the luciferase-labeled competitor and capable of binding to the target analyte but not the competitor;
• and
• (d) an inhibitor of the luciferase label, wherein the inhibitor is capable of binding to the luciferase-labeled competitor and reducing the signal from the luciferase label.