Autoimmune diseases – recognizing classic examples Which of the following conditions are recognized examples of autoimmune disease in clinical immunology?

Introduction / Context:
Autoimmune diseases arise when the immune system loses tolerance to self-antigens and mounts pathogenic responses against host tissues. Recognizing prototypical examples is essential for clinicians, microbiologists, and exam candidates.

Given Data / Assumptions:

• Autoimmunity includes organ-specific and systemic disorders.
• Multiple immune mechanisms may be involved (autoantibodies, immune complexes, T-cell–mediated injury).
• The listed conditions are common textbook entities.

Concept / Approach:
Rheumatoid arthritis involves autoantibodies (e.g., rheumatoid factor, anti-CCP) and synovial inflammation. Systemic lupus erythematosus is a systemic immune complex disease with diverse autoantibodies (ANA, anti-dsDNA, anti-Sm). Polyarteritis nodosa is a necrotizing vasculitis of medium-sized arteries often associated with immune-mediated injury. Because each is a well-established autoimmune disorder, the inclusive option is correct.

Step-by-Step Solution:
Identify each listed disease and its autoimmune basis.Confirm that all three are standard autoimmune exemplars.Select “All of the above.”

Verification / Alternative check:
Standard rheumatology and immunology texts classify RA, SLE, and PAN as autoimmune, supporting the selection.

Why Other Options Are Wrong:

• Individual options (RA, SLE, PAN) are correct but incomplete.
• “None” contradicts established nosology.

Common Pitfalls:
Confusing PAN with ANCA-associated vasculitides; PAN is classically ANCA-negative but still immune-mediated and placed within autoimmune/immune complex disorders.

Final Answer:
All of the above.