Final answer:
A positive ANA test shows the presence of autoantibodies targeting the cell nucleus, suggesting an autoimmune disorder. The IFA technique involves antibodies tagged with fluorescent dye binding to human immunoglobulins,
Step-by-step explanation:
A positive result of an antinuclear antibody (ANA) test indicates the presence of autoantibodies that target normal proteins within the nucleus of cells. The indirect fluorescent antibody (IFA) technique is commonly used for ANA testing. In this process, cells are fixed to a slide, exposed to a patient's serum, and then to a fluorescent anti-human immunoglobulin (mAb) specific for human antibodies. If ANAs are present, the mAb will bind to them, and the resulting complex will fluoresce, indicating a positive result. The ANA test is particularly important for diagnosing autoimmune diseases such as systemic lupus erythematosus (SLE), as the immune system mistakenly targets the body's own cells.
The fluorescent antibody in an IFA for ANA binds to human immunoglobulin (specifically IgG) that is potentially bound to nuclear antigens. A visible fluorescence around the nucleus confirms the presence of ANAs. While some ANA can be found in healthy individuals, a higher titer is often suggestive of an autoimmune disorder, particularly if corresponding symptoms are present.