Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic. An elastic band is placed around the upper arm to apply pressure and cause the vein to swell with blood. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding. In infants or young children, the area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. A bandage may be applied to the puncture site if there is any bleeding. Immunofluorescence is a laboratory technique. The exact technique may vary depending on the specific antibody that is being investigated and between different laboratories. In general, cells, tissue, or some other substance is placed onto microscope slides. A small amount of sample containing antibodies (typically serum, a liquid portion of blood) is placed over the cells or tissue, allowing the antibodies that are specific for the particular tissue or cellular antigens to bind. The serum is washed away, and a second antibody that binds to human antibodies (often made in another animal species such as rabbits or goats) is applied to the slide. This second antibody has a fluorescent dye chemically linked to it. If the person's serum has antibodies that bind to the tissue or cells, a bright fluorescence can be seen by use of a special microscope.
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