Screening for autoimmune diseases is often performed with the antinuclear antibody (ANA) test in which patient serum is incubated with a tissue substrate to which any autoantibodies to nuclear antigens will bind. Then, a fluorosceinated antibody is added and the tissue is observed under fluorescence microscopy to see if staining is present. Seen here is the typical "homogenous" pattern of nuclear staining of a positive ANA.