The researchers managed to fix the pollen protein on the wall of the test tube, inject an antibody (IgG4) to bind it to the pollen protein, wash off the excess IgG4, then add the mite protein labeled with radioactive iodine, and finally rinse it with water. It was found that the radioactive labeled mite protein adhered to the wall of the test tube, which meant that the antibody bound to two different antigens.
Which of the following statements conforms to the above context?
excess IgG4 refers to IgG4 that does not bind to pollen protein after injection into the test tube