Immunology · Year 2 · from Immunology

Case 2: Biologics and Immunosuppression Complications

Patient Presentation

Demographics: 62-year-old female

Chief Complaint: Night sweats, weight loss, and chronic cough for 2 months

History of Present Illness: The patient has rheumatoid arthritis treated with adalimumab (anti-TNF-alpha) for the past 3 years with excellent disease control. Over the past 2 months, she has developed progressive fatigue, night sweats, unintentional weight loss (15 pounds), and productive cough. She recalls her TB screening was negative before starting adalimumab.

Past Medical History:

  • Rheumatoid arthritis (10 years)
  • Osteoporosis
  • Former smoker (30 pack-years, quit 5 years ago)

Medications:

  • Adalimumab 40 mg every 2 weeks
  • Methotrexate 15 mg weekly
  • Folic acid 1 mg daily
  • Alendronate 70 mg weekly

Physical Examination:

  • Temperature: 37.8C (low-grade fever)
  • Weight: 58 kg (down from 65 kg)
  • General: Cachectic appearance
  • Lungs: Right upper lobe crackles
  • Lymph nodes: Right supraclavicular lymphadenopathy

Workup and Results

Laboratory Studies:

  • WBC: 6,200/mcL
  • Hemoglobin: 10.8 g/dL
  • ESR: 78 mm/hr
  • CRP: 45 mg/L
  • HIV: Negative

Chest X-ray:

  • Right upper lobe infiltrate with cavitation

Sputum Studies:

  • AFB smear: Positive for acid-fast bacilli
  • TB PCR: Positive for Mycobacterium tuberculosis

Prior Records:

  • TB skin test (before adalimumab): 4 mm (negative)
  • QuantiFERON-TB Gold: Not performed

Clinical Image

Chest X-ray demonstrating right upper lobe cavitary lesion consistent with pulmonary tuberculosis. This classic presentation occurs with reactivation TB, which is increased in patients on TNF-alpha inhibitors.

Diagnosis

Reactivation Pulmonary Tuberculosis in Setting of TNF-alpha Inhibitor Therapy

Risk factors:

  • Anti-TNF therapy (adalimumab)
  • Possible latent TB with false-negative initial screening
  • Former smoker

Discussion

This case illustrates immunosuppression risks:

  • TB Screening Requirement: The lecture emphasizes that patients must be screened for latent tuberculosis before starting TNF inhibitor therapy. TNF-alpha is essential for granuloma formation and TB containment.
  • TNF Inhibitor Mechanism: The lecture describes how TNF inhibitors block the pro-inflammatory cytokine TNF-alpha, providing benefit in autoimmune diseases but impairing host defense against intracellular pathogens, particularly mycobacteria.
  • Screening Limitations: TST can have false negatives in immunocompromised patients. The lecture notes that interferon-gamma release assays (IGRAs) like QuantiFERON may be more sensitive in this setting.
  • Reactivation Risk: Anti-TNF therapy increases TB risk 2-8 fold, with most cases occurring in the first year but risk persisting throughout therapy.

Treatment Plan

  1. Discontinue Adalimumab:
  • Stop immediately
  • Do not restart until TB adequately treated
  1. TB Treatment:
  • Standard 4-drug regimen (RIPE: rifampin, isoniazid, pyrazinamide, ethambutol)
  • Duration: 6-9 months minimum
  • Directly observed therapy recommended
  1. RA Management:
  • Consider alternative non-biologic DMARDs during TB treatment
  • Avoid all TNF inhibitors
  • Rituximab (anti-CD20) may be safer alternative after TB treated
  1. Contact Investigation:
  • Household contact screening
  • Report to public health
  1. Future Considerations:
  • If TNF inhibitor ever reconsidered, complete full TB treatment first
  • Repeat LTBI screening before any future biologic

Teaching Points

  1. Screen for latent TB before starting TNF inhibitors (TST or IGRA)
  2. TNF-alpha is essential for granuloma formation and TB containment
  3. TNF inhibitor-associated TB is usually reactivation, not primary infection
  4. Anti-TNF therapy increases TB risk 2-8 fold
  5. Treat latent TB infection before starting TNF inhibitors

All cases for this lecture as Markdown