Which finding is most characteristic of autoimmune disease in immunology lab panels?

• A. Absence of autoantibodies
• B. Presence of autoantibodies such as ANA, RF, anti-dsDNA, anti-CCP
• C. Exclusively elevated IgA
• D. Decreased C-reactive protein

Answer: (B)

Autoimmune diseases are diagnosed in part by antibodies that target the body's own tissues. In immunology panels, the most indicative finding is the presence of autoantibodies. Antinuclear antibodies (ANA) serve as a broad screen for systemic autoimmune conditions, while rheumatoid factor (RF) is commonly seen in rheumatoid arthritis. Antibodies directed against doubled-stranded DNA (anti-dsDNA) are strongly associated with systemic lupus erythematosus, and anti-CCP antibodies are highly specific for rheumatoid arthritis. Together, detecting these autoantibodies in a patient’s serum provides a characteristic autoimmune signal in the lab.

Other patterns aren’t as specific: absence of autoantibodies would argue against autoimmune disease, elevated IgA alone isn’t diagnostic, and C-reactive protein is a general inflammatory marker that can rise in many conditions without proving autoimmunity.