Line Blot Immunoassay for Autoantibodies (e.g., Antinuclear Antibodies, ANA)

What This Test Measures

The line blot immunoassay detects a range of autoantibodies, including common markers like antinuclear antibodies (ANA), anti-double-stranded DNA (anti-dsDNA), and others that may signal autoimmune activity. The test uses a fluid sample (usually serum) to identify these antibodies by binding to specific targets on a membrane, creating visible lines if antibodies are present.

Why It’s Ordered

Your healthcare provider may order this test if you have symptoms like joint pain, fatigue, rash, or unexplained organ issues that could suggest an autoimmune condition. It’s also used to monitor known autoimmune diseases or screen for conditions like lupus, Sjögren’s syndrome, or mixed connective tissue disease.

Sample Collection and Preparation

A blood sample is typically drawn from a vein in your arm. The serum portion is separated and sent to the lab for testing. The line blot assay involves applying the serum to a membrane with immobilized antigens, allowing antibodies to bind if present.

Test Results and Interpretation

Results are qualitative (positive or negative) and may show multiple lines if multiple autoantibodies are detected. A positive result suggests a higher likelihood of an autoimmune condition, but further testing or clinical correlation is needed for diagnosis.