SSB/La Antibody (AI) Unit Converter

The SSB/La ENA Ab test measures autoantibodies directed against the SSB/La antigen, an extractable nuclear antigen (ENA). These antibodies are produced when the immune system mistakenly targets the body's own La protein, an RNA-binding phosphoprotein found inside cells.

The La protein plays a role in RNA processing and protection of newly made RNA molecules from degradation. When the immune system produces antibodies against it, this signals autoimmune activity.

SSB/La antibodies are almost always found alongside SSA/Ro antibodies. It is rare for SSB/La to be positive without SSA/Ro also being present. Results are reported as an Antibody Index (AI), with values below 1.0 AI considered normal.

Anti-SSB/La antibodies are produced by B lymphocytes and plasma cells of the immune system. Their production is driven by a loss of immune tolerance to the La protein, which can be triggered by genetic susceptibility, viral infections, or cellular damage that exposes normally intracellular antigens.