Lateral flow immunoassay for measuring functional C1-esterase inhibitor (C1-INH) in plasma samples

A device for detecting and/or quantifying functional C1-esterase inhibitor (fC1-INH) in a human sample, the device comprising:

• (i) a conjugate pad comprising a first zone and a second zone, wherein the first zone comprises a first agent and the second zone comprises a second agent, and
• (ii) a membrane, which is in communication with the conjugate pad, wherein the membrane comprises a third zone, on which a third agent is immobilized,
• wherein the first agent is a functional C1 inhibitor (fC1-INH) binding agent or a C1 inhibitor (C1-INH) binding agent and the second agent is a fC1-INH binding agent or a C1-INH binding agent,
• the first agent and the second agent being different from each other;
• wherein the third agent is a capture agent capable of binding to a docking agent,
• wherein one of the fC1-INH binding agent and the C1-INH binding agent is conjugated to a detectable label, and one of the fC1-INH binding agent and the C1-INH binding agent is conjugated to the docking agent, the detectable label and the docking agent being conjugated to a different agent;
• and
• wherein the conjugate pad further comprises a fourth zone for placing the human sample, which flows through the device in the order of the first zone, the second zone, and the third zone.