A means of identifying and quantifying the amount of an antigen in a specimen in which a fluorescently labeled antibody is mixed with a sample thought to contain the antigen is exposed to polarized light. Bound fluorescently labeled antibody reacts to polarized light in a characteristic fashion not demonstrated by unbound antibody, allowing for identification and measurement of the ligand.
An antigen-antibody analysis using fluorescent-tagged antigens. The technique is based on the principle that antigens, which are small molecules, rotate rapidly and therefore emit randomly polarized fluorescence, whereas antigens bound to antibodies, which are large molecules, rotate slowly and produce highly polarized fluorescence. When many unbound antigens are present, there will be less polarized light.