How Lupus Attacks the Body: Organs, Symptoms, and Treatment

An Immune System That Cannot Tell Friend From Foe

An estimated 1.5 million Americans and 5 million people worldwide live with some form of lupus, according to the Lupus Foundation of America. Systemic lupus erythematosus (SLE), the most common and serious type, accounts for roughly 70 percent of all cases. The disease disproportionately affects women of reproductive age, with a female-to-male ratio of approximately 9 to 1. Black, Hispanic, and Asian women face two to three times higher risk than white women.

SLE is a systemic autoimmune disease. The immune system generates antibodies against the body's own DNA, proteins, and cell components. These autoantibodies form immune complexes that deposit in tissues throughout the body, triggering inflammation and damage in virtually any organ. No two lupus patients present identically.

The Organs Under Siege

Lupus earns the nickname 'the great imitator' because it mimics dozens of other conditions. The disease can target the skin, joints, kidneys, brain, heart, lungs, and blood cells simultaneously or sequentially.

Lupus nephritis deserves special attention. It develops when immune complexes deposit in the glomeruli, the kidney's filtering units. Left untreated, it progresses to end-stage renal disease. Kidney biopsy classifies nephritis into six classes (ISN/RPS system), guiding treatment intensity. Class III and IV (focal and diffuse proliferative) require aggressive immunosuppression.

The Butterfly Rash and Beyond: Skin Manifestations

The malar rash stretches across both cheeks and the bridge of the nose, sparing the nasolabial folds. It appears in roughly 50 percent of SLE patients. Sunlight triggers or worsens it. Photosensitivity affects up to 70 percent of patients, making UV protection essential.

Discoid lupus produces thick, scaly plaques that can scar permanently. It may occur with or without systemic disease. Other skin findings include:

• Oral and nasal ulcers, usually painless
• Raynaud's phenomenon: fingers turn white then blue in cold temperatures
• Alopecia, often diffuse and non-scarring
• Subacute cutaneous lupus: annular or papulosquamous lesions on sun-exposed areas
• Livedo reticularis: a lace-like purplish discoloration of the skin

Diagnosis Requires Meeting Multiple Criteria

No single test diagnoses lupus. The 2019 EULAR/ACR classification criteria use a weighted scoring system. A positive antinuclear antibody (ANA) test serves as the entry criterion. Then clinical and immunological domains are scored. A total score of 10 or higher classifies a patient as having SLE.

ANA testing has high sensitivity (over 95 percent) but low specificity. Many healthy people test ANA-positive. More specific antibodies refine the diagnosis:

• Anti-dsDNA: highly specific for SLE, correlates with nephritis activity
• Anti-Smith (anti-Sm): most specific antibody for SLE, present in 20-30%
• Anti-phospholipid antibodies: associated with clotting risk
• Low complement levels (C3, C4): indicate active immune complex consumption
• Anti-Ro/SSA and Anti-La/SSB: associated with neonatal lupus and Sjogren's overlap

EULAR/ACR 2019 Scoring Domains

Treatment: Balancing Suppression With Safety

Hydroxychloroquine is the backbone of lupus treatment. Every SLE patient without contraindications should take it. The drug reduces flares by 50 percent, lowers damage accrual, improves survival, and decreases thrombosis risk. Annual eye exams monitor for rare retinal toxicity.

Corticosteroids control acute flares. Minimizing their use is a central treatment goal because chronic steroids drive osteoporosis, diabetes, cataracts, and infections. Steroid-sparing immunosuppressants include mycophenolate mofetil (first-line for lupus nephritis), azathioprine, cyclophosphamide (for severe organ involvement), and calcineurin inhibitors.

Belimumab, approved in 2011, was the first biologic for SLE. It blocks B-lymphocyte stimulator (BLyS), reducing autoantibody production. Voclosporin, approved in 2021, adds a calcineurin inhibitor option specifically for lupus nephritis. Anifrolumab, targeting the type I interferon pathway, was approved in 2021 for moderate-to-severe SLE.

Flares, Remission, and the Long Road Ahead

Lupus follows an unpredictable relapsing-remitting course. Triggers for flares include UV exposure, infections, stress, pregnancy, and medication non-adherence. The Lupus Low Disease Activity State (LLDAS) and DORIS remission criteria give clinicians standardized targets.

Survival has improved dramatically. Five-year survival exceeded 95 percent in developed countries by the 2010s, up from roughly 50 percent in the 1950s. The main causes of death have shifted from uncontrolled disease to cardiovascular events and infections related to immunosuppressive therapy. Women with lupus face a cardiovascular risk equivalent to someone 20 years older. Aggressive risk factor management is essential. This article is for informational purposes only. Consult a qualified professional.