Immunofluorescence is a lab test that may be ordered by your physician for purposes of determining the presence of certain auto-immune diseases of the skin and other illnesses according to the presence and amount of certain antibodies (called antinuclear antibodies) in the blood. Here, a small sample of the patient’s blood serum is applied to cells that are mounted on a slide. The antibodies for specific tissues or cellular antigens are then allowed to bind and the serum is washed off, followed by the application of a second antibody that has a fluorescent dye and will bind with human antibodies. When certain antibodies are present, they will have a fluorescent appearance when viewed by a special microscope. Diseases that this test is used to detect include Colorado tick fever, infectious mononucleosis, Lyme disease, Rocky Mountain Spotted Fever, Q fever, and more.