The Allergy Johnson Grass lab test is a test performed on a sample of blood. It measure the sample for to detect the level of IgE antibodies. The test is a precise method of measuring the concentration of antibodies in the blood. Thus, it not only detects Johnson Grass Sorghum Grass Allergy but also helps in confirming the allergy post the treatment in case of any relapse. The disease or the allergy is also known as Allergy Johnson Grass Fluorescence Assay.