Autoantibodies commonly detected in systemic lupus erythematosus are directed against what type of antigen?

• A. Surface antigens of bone marrow stem cells
• B. Nuclear antigens
• C. Mitochondrial antigens
• D. Myelin antigens

Answer: (B)

Autoantibodies in systemic lupus erythematosus primarily target components inside the cell nucleus. This is why ANA testing is a hallmark of SLE, as many antibodies react with nuclear antigens such as DNA, histones, and various nuclear proteins (like Sm and RNP). The binding of these anti-nuclear antibodies forms immune complexes that circulate and can deposit in tissues, driving inflammation and organ damage, notably the kidneys in lupus nephritis.

Antibodies against surface antigens of bone marrow stem cells aren’t typical for SLE and would point to other conditions. Antibodies to mitochondrial antigens are characteristic of primary biliary cholangitis, not lupus. Antibodies to myelin antigens are associated with demyelinating diseases such as multiple sclerosis. Therefore, the type of antigen most commonly targeted in SLE is nuclear.