Linked Immunosorbent assay.
I've done thousands, developed some.
You take a plastic dish. Add something to it then add an antibody
to what is on the dish. If that something is there and the antibody binds it, you got an antibody stuck on a dish. Then, add something that lights up if an antibody is on the dish.
Can be used to find something (if u have antibody to it)
Also can show immunity to it.