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Jo-1 Antibody

Published: July 27, 2026Updated: August 25, 2026

Jo-1 antibody is a marker used to aid in the diagnosis of polymyositis and dermatomyositis, which are inflammatory muscle diseases.

Quick summary

Jo-1 antibody levels above 20 U/mL may indicate polymyositis or dermatomyositis.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 25, 2026Editorial policy

Key facts at a glance

Units
U/mL
Clinical utility
diagnostic
Result kind
quantitative
FDA-cleared
Roche Jo-1, Abbott Jo-1, Siemens Jo-1
interpretation: {"text":"0–20 U/mL: Jo-1 antibody levels within this range are not indicative of polymyositis or dermatomyositis.","label":"Normal"}; {"text":">20 U/mL: Levels above the reference range may suggest the presence of polymyositis, dermatomyositis, or related conditions.","label":"Elevated"}

Jo-1 antibody is one of the most common myositis-specific autoantibodies. It targets histidyl-tRNA synthetase, an enzyme involved in protein synthesis.

Elevated levels of Jo-1 antibody are frequently associated with interstitial lung disease and are found in approximately 20-30% of patients with polymyositis and dermatomyositis.

Testing for Jo-1 antibody is crucial for differentiating these conditions from other neuromuscular disorders and guiding appropriate treatment strategies.

Frequently asked questions

What is the role of Jo-1 antibody in disease diagnosis?
Jo-1 antibody testing helps in the diagnosis of polymyositis and dermatomyositis by detecting autoantibodies associated with these conditions.
Can Jo-1 antibody levels change over time?
Yes, Jo-1 antibody levels can fluctuate with disease activity, making them useful for monitoring treatment response and disease progression.
  1. 1
    Polymyositis and Dermatomyositis - MedlinePlusSource
  2. 2
    Jo-1 Antibody - Lab Tests OnlineSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 25, 2026. · Read our editorial policy