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Test Code JO1 Jo 1 Antibodies, IgG, Serum

Important Note

Beaker/EPIC order code is LAB770

Performing Laboratory

Mayo Medical Laboratories in Rochester

Reporting Name

Jo 1 Ab, IgG, S

Specimen Type


Specimen Required


Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 0.50 mL

Reject Due To


Mild OK; Gross reject


Mild OK; Gross reject


Mild OK; Gross OK



Specimen Stability Information

Specimen Type Temperature Time
Serum Refrigerated (preferred) 21 days
  Frozen  21 days

Specimen Minimum Volume

0.35 mL

Day(s) and Time(s) Performed

Monday through Saturday; 4 p.m., Sunday; 11a.m.

Specimen Retention Time

7 days

Analytic Time

1 day

Reference Values

<1.0 U (negative)

≥1.0 U (positive)

Reference values apply to all ages.

Useful For

Evaluating patients with signs and symptoms compatible with a connective tissue disease, especially those patients with muscle pain and limb weakness, concomitant pulmonary signs and symptoms, Raynaud phenomenon, and arthritis

Testing Algorithm

See Connective Tissue Disease Cascade (CTDC) in Special Instructions.

Method Name

Multiplex Flow Immunoassay

Test Classification

This test has been cleared or approved by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
JO1 Jo 1 Ab, IgG, S 33571-1


Result ID Test Result Name Result LOINC Value
JO1 Jo 1 Ab, IgG, S 33571-1

Clinical Information

Jo 1 (histidyl tRNA synthetase) is a member of the amino acyl-tRNA synthetase family of enzymes found in all nucleated cells. Jo 1 antibodies in patients with polymyositis bind to conformational epitopes of the enzyme protein and inhibit its catalytic activity in vitro.(1)


Jo 1 antibodies are a marker for the disease polymyositis, and occur most commonly in myositis patients who also have interstitial lung disease. The antibodies occur in up to 50% of patients with interstitial pulmonary fibrosis and symmetrical polyarthritis.(2)


See Connective Tissue Disease Cascade (CTDC) in Special Instructions.


A positive result for Jo 1 antibodies is consistent with the diagnosis of polymyositis and suggests an increased risk of pulmonary involvement with fibrosis in such patients.


Testing for antibodies to Jo 1 is not useful in patients with a negative test for antinuclear antibodies.


A negative test for Jo 1 antibodies does not exclude the diagnosis of polymyositis or dermatomyositis.

Clinical Reference

1. Targoff I: Autoantibodies in polymyositis. Rheum Dis Clin North Am 1992;18:455

2. Leff R, Sherman J, Plotz P: Chapter 65: Inflammatory muscle diseases. In Clinical Immunology Principles and Practice, Second edition. Edited by R Rich, T Fleisher, W Shearer, B Kotzin, et al. St. Louis, Mosby-Year Book, 2001, pp 65.1-65.8

Method Description

Recombinant Jo 1 antigen is coupled covalently to polystyrene microspheres, which are impregnated with fluorescent dyes to create a unique fluorescent signature. Jo 1 antibodies, if present in diluted serum, bind to the Jo 1 antigen on the microspheres. The microspheres are washed to remove extraneous serum proteins. Phycoerythrin (PE)-conjugated antihuman IgG antibody is then added to detect IgG anti-Jo 1 bound to the microspheres. The microspheres are washed to remove unbound conjugate, and bound conjugate is detected by laser photometry. A primary laser reveals the fluorescent signature of each microsphere to distinguish it from microspheres that are labeled with other antigens, and a secondary laser reveals the level of PE fluorescence associated with each microsphere. Results are calculated by comparing the median fluorescence response for Jo 1 microspheres to a 4-point calibration curve. (Package insert: Bioplex 2200 ANA Screen. Bio-Rad Laboratories, Hercules, CA)