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Macrophage Activation Syndrome: JAK Inhibitor Therapy

Targeted approach for refractory secondary HLH in rheumatic disease

Written by: Saygı Hospital Health Guide Editorial Board
Last updated:

This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.

References (5)

This content is for informational purposes only and does not constitute medical advice. You can book an appointment at our Hematoloji department. Book Appointment →

What is Macrophage Activation Syndrome: JAK Inhibitor Therapy?

Macrophage activation syndrome (MAS) is a form of secondary HLH occurring in rheumatic diseases.

Most commonly complicates systemic juvenile idiopathic arthritis, adult-onset Still disease, and systemic lupus erythematosus.

Driven by uncontrolled cytokine signaling through JAK-STAT pathways, especially interferon-gamma and IL-6.

Diagnostic criteria include high ferritin, falling cell counts, hypofibrinogenemia, and hepatic dysfunction.

JAK inhibitors (ruxolitinib, baricitinib) targeting JAK-STAT signaling show promise in refractory cases.

Symptoms

High persistent fever despite glucocorticoid treatment for underlying rheumatic disease.
Sudden drop in white cell count, hemoglobin, and platelets.
Marked hyperferritinemia rising rapidly over days.
Liver dysfunction with elevated transaminases and coagulopathy.
Splenomegaly, lymphadenopathy, and central nervous system involvement in severe cases.

Risk Factors

Active systemic juvenile idiopathic arthritis flare with macrophage activation features.
Adult-onset Still disease, especially during disease flares.
Recent infection (especially viral) triggering MAS in autoimmune patients.
Genetic polymorphisms in HLH-related genes increasing susceptibility.
Immunosuppression dose changes preceding MAS onset.

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

  • Sudden worsening of fever, fatigue, or new bleeding in known rheumatic disease.
  • Falling cell counts on routine monitoring during rheumatic disease management.
  • Rapidly rising ferritin levels suggesting MAS evolution.
  • Confusion or altered mental status during disease flare.
  • Worsening liver enzymes or new coagulopathy.

Treatment Methods

01
High-dose corticosteroids (methylprednisolone pulse 1 g daily for 3 days) as initial therapy.
02
Cyclosporine or anakinra as second-line agents for refractory cases.
03
Ruxolitinib oral 5 to 25 mg twice daily considered for steroid-refractory or relapsing MAS.
04
Etoposide (HLH-94 protocol) in life-threatening cases unresponsive to first-line agents.
05
Treatment of underlying rheumatic disease essential for sustained remission.

Which Department to Visit?

You can visit our Hematoloji department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.