Glossary
Anti-Jo-1 antibody
This is one antibody, found in about half the people with antisynthetase syndrome, and it's the commonest of its family. What it changes is mostly how the illness opens and how fast it gets named. It tells you more about which test somebody happened to order first than it does about how things are likely to go from here.
What the research found.
One study followed 205 people with antisynthetase syndrome and counted which antibodies they had. Anti-Jo1 was present in 49.3 percent of them, which is about half the group. Anti-PL7 came next at 19.0 percent, then anti-EJ at 11.2 percent, anti-PL12 at 10.2 percent, and anti-OJ at 3.4 percent.
One Hungarian study followed 49 people who had tested positive for this particular antibody. Muscle inflammation was present in 100 percent of them, joint inflammation reached 88 percent, and lung scarring reached 73 percent. Raynaud's reached 65 percent, fever reached 43 percent, and mechanic's hands reached 33 percent, so the list runs well beyond muscle.
One study followed 103 people who had anti-Jo-1 antibodies together with lung disease, and ten-year survival there was 68 percent. Non-specific interstitial pneumonia was the commonest imaging picture in that group, at 52 percent. Restriction on lung function testing was present in 98 percent of them, which is nearly everybody.
One study looked at 118 people with definite dermatomyositis, and anti-Jo-1 was present in 10 of them. That works out at 8.5 percent of the group. Those 10 had more mechanic's hands, more joint trouble, and more lung disease, with fewer skin findings, and not one of them went into remission.
What this antibody is
Anti-Jo-1 is an antibody that your immune system has made against one of your own enzymes. That's what an autoantibody is, and the name is the whole of the idea. The enzyme it targets helps build proteins inside your cells, and a family of similar antibodies aim at related enzymes.
Together those antibodies are what define antisynthetase syndrome as an illness. Anti-Jo-1 is much the commonest of that family, and it's also the one most laboratories test for first. That second fact turns out to count for a good deal more than you would expect it to.
How common it is
It's common within this illness and uncommon outside it, and the two figures are worth seeing together. They explain why this test gets ordered when it does. One study followed 205 people with antisynthetase syndrome, where anti-Jo1 was present in 49.3 percent of them.
Anti-PL7 came next at 19.0 percent, then anti-EJ at 11.2 percent, anti-PL12 at 10.2 percent, and anti-OJ at 3.4 percent. Step back to the wider group and the numbers get small. One study covered 460 people with inflammatory muscle disease, and any antibody from this family showed in 51 of them, or 11.1 percent. Another covered 118 people with definite dermatomyositis, and anti-Jo-1 showed in 10 of them, or 8.5 percent.
What a positive result predicts
It predicts a mix of problems rather than one organ. One Hungarian study followed 49 people who had tested positive, and it counted what each one of them had. Muscle swelling was there in 100 percent of them, joint swelling reached 88 percent, and lung scarring reached 73 percent. Raynaud's reached 65 percent. Fever reached 43 percent, mechanic's hands reached 33 percent, and trouble swallowing reached 12 percent, so the list covers four organs and a blood vessel problem besides.
A separate study looked at the question from the other direction entirely. It covered 118 people with definite dermatomyositis, of whom 10 turned out to have anti-Jo-1. That group had more mechanic's hands, more joint trouble, and more lung disease than the rest, with fewer skin findings to show for it.
One more finding from a third study sits alongside those. A Chinese study followed 88 people, where arthritis was more frequent in the anti-Jo-1 group than in the anti-PL-7 group, and that held against the anti-EJ group as well. Those came in at P equals 0.004 and P equals 0.002.
What a negative result means
It means less than most people assume, and this is the thing worth taking away from the whole page. It follows straight on from the section above it. About half of people with antisynthetase syndrome have a different antibody, and those are separate tests that aren't always ordered together.
The newer ones among them aren't available in every laboratory either. So say the picture still fits and your own anti-Jo-1 test came back negative. That's a reason to ask a question rather than to close the file, and which of the others were checked is a fair thing to ask.
How fast the diagnosis comes
One study makes the practical consequence of all this clear enough to put a number on. It followed 205 people and timed the gap between their first symptom and the day they were finally given a diagnosis to work with. For people without anti-Jo1 the median was five months, and for people with it the median came in at three.
That difference probably says more about which test gets ordered first than it does about the illness itself. Two months is still two months out of somebody's life. If you waited that long, it's worth knowing the delay wasn't your fault and it wasn't anybody's oversight either.
What it means for your outlook
Having this antibody doesn't appear to make things worse, and that's the honest answer. The evidence behind it runs thinner than you'd like. The strongest source is a study of 828 people that compared the antibody groups directly and found survival unchanged by which one a person had.
A much smaller study of 28 people found better survival in the anti-Jo-1 group. Its P value was 0.05, so that's 28 people and a P value sitting right on the line where significance is usually drawn. It's a hint rather than a finding, and it's worth reading as one.
One separate observation is worth setting beside those two. A study of 205 people found joint involvement was protective against death, and joint involvement happens to be commoner in people with this antibody. That study didn't connect those two facts, so neither should you, though it's the direction things point.
The lungs
This is the part that counts for the most, and it holds across the whole syndrome rather than just this antibody. One study followed that side of it closely enough to be worth reading. It followed 103 people with anti-Jo-1 antibodies and lung disease, whose mean age was 49.2 and of whom 70 percent were women. Ten-year survival in that group came in at 68 percent.
Non-specific interstitial pneumonia was the commonest imaging picture there, at 52 percent. That picture overlapping with organizing pneumonia came next in the ranking, at 22 percent. Restriction on lung function testing showed in 98 percent of them, which is very nearly everybody who was tested.
One detail about the timing of all this is worth knowing about. In about half of that group, the two diagnoses came within six months of each other. So the lungs aren't usually a late development, and they're often part of how the illness announces itself in the first place.
Why the level gets rechecked
Your notes may hold a number rather than just a yes or a no. That number moves with other measures, and one study looked at which ones. One Hungarian study of 49 people found the anti-Jo-1 level correlated significantly with creatine kinase and with C-reactive protein, both at the start and through the course of the illness.
Creatine kinase is the blood test that reflects muscle damage. That's why the level gets rechecked alongside the rest of your results. It isn't a reason to track your own number between visits, because a single value out of context tells you very little.
Common misconceptions.
Myth. A negative anti-Jo-1 test rules out antisynthetase syndrome.
Reality. It rules out one antibody rather than the illness behind it. One study of 205 people found anti-Jo1 in 49.3 percent, so about half had something else, which means anti-PL7, anti-EJ, anti-PL12, or anti-OJ. Those are tested separately and aren't always ordered together, so if the picture fits and your test was negative, ask which others were checked.
Myth. Testing positive means a worse outcome.
Reality. The evidence points the other way, though not strongly. One study of 828 people found survival unchanged by which antibody a person had, and a second study of 28 people found better survival in the anti-Jo-1 group, at a P value of 0.05. A third, of 205 people, found joint trouble protective, and joint trouble is commoner with this antibody.
Myth. It's a muscle antibody, so it means muscle disease.
Reality. It predicts a good deal more than muscle. One Hungarian study followed 49 people who had it, where muscle inflammation was there in 100 percent, joint swelling reached 88 percent, and lung scarring reached 73 percent. A separate study covered 118 people with dermatomyositis, and the 10 who had this antibody had more joint trouble and more lung disease.
Myth. The antibody level is just a yes or no.
Reality. It tracks with other measures rather than sitting still. One Hungarian study looked at the anti-Jo-1 level and found it correlated with creatine kinase and with C-reactive protein, both at the start and through the illness. That isn't a reason to watch the number yourself, and it is the reason the number gets rechecked.
Myth. It's found in everybody with muscle inflammation.
Reality. It's uncommon even among people with muscle inflammation. One study covered 460 people with inflammatory muscle disease, and any antisynthetase antibody showed in 51 of them, or 11.1 percent. Anti-Jo-1 is about half of those, and a second study of 118 people with definite dermatomyositis found it in 10, or 8.5 percent.
Related terms.
- Antisynthetase syndrome, the illness this antibody defines.
- Myositis, the wider group of muscle inflammation illnesses.
- Myositis blood tests, for the other results measured alongside this one.
Questions patients ask.
What is anti-Jo-1?
It's an antibody that your own immune system has made against one of your own enzymes. The enzyme in question helps build proteins inside your cells, and a whole family of antibodies target enzymes like it. Together that family is what defines antisynthetase syndrome. Anti-Jo-1 is much the commonest of them, and it's also the one most laboratories test for first, which turns out to count.
How common is it?
Common within this illness, and distinctly uncommon outside it. One study covered 205 people with antisynthetase syndrome, where anti-Jo1 showed in 49.3 percent of the group. A second covered 460 people with inflammatory muscle disease of any kind, where any antibody from this family showed in only 11.1 percent. A third covered 118 people with definite dermatomyositis, where anti-Jo-1 showed in 8.5 percent.
What does a positive result predict?
A particular mix of problems rather than one organ on its own. One Hungarian study followed 49 people who had it, where muscle swelling was there in 100 percent, joint swelling reached 88 percent, and lung scarring reached 73 percent. Raynaud's reached 65 percent, fever reached 43 percent, mechanic's hands reached 33 percent, and trouble swallowing reached 12 percent.
Does a negative result rule it out?
No, and this is the thing worth taking away from the page. About half of people with antisynthetase syndrome have a different antibody from this family, and those are tested separately rather than always together. If your picture fits and this one came back negative, ask which of the others were checked.
Does it change how fast I get diagnosed?
It appears to, on one study at least. One study of 205 people measured the time from first symptom to diagnosis, and for people without anti-Jo1 the median was five months while for those with it the median was three. That difference probably reflects which test gets ordered first rather than anything about the illness.
Is my outlook worse with it?
The evidence on this page doesn't say so, and there isn't much of it. One study of 828 people found that survival wasn't influenced by which antisynthetase antibody a person happened to have. One study of 28 people found better survival in the anti-Jo-1 group, at a P value sitting right on 0.05. That's a small study and a borderline P value, so it's worth holding loosely.
Why does my level keep getting checked?
Because it moves along with other measures rather than standing alone. One Hungarian study followed 49 people, and the anti-Jo-1 level correlated with creatine kinase and with C-reactive protein, both at the start and through the illness. Creatine kinase is the blood test that reflects muscle damage. So your level is one of several things watched together rather than a score to track on your own.
What about my lungs?
That's the part of this illness that counts for the most, and it's worth its own section. One study followed 103 people with anti-Jo-1 and lung disease, where ten-year survival was 68 percent. Non-specific interstitial pneumonia was the commonest imaging picture, at 52 percent. In about half of them the two diagnoses came within six months of each other, so the lungs aren't usually a late development.
References.
- Tang HS; Tang IYK; Ho RTC et al. Clinical heterogeneity and prognostic factors of anti-synthetase syndrome: a multi-centred retrospective cohort study. Rheumatology (Oxford). 2025;64:212-220. 10.1093/rheumatology/kead671Multicentre retrospective longitudinal cohort of 205 patients meeting Connor's or Solomon's criteria for antisynthetase syndrome
- Szabó K; Bodoki L; Nagy-Vincze M et al. Effect of Genetic and Laboratory Findings on Clinical Course of Antisynthetase Syndrome in a Hungarian Cohort. Biomed Res Int. 2018;2018:6416378. 10.1155/2018/6416378Retrospective study of the clinical database of 49 anti-Jo-1 positive antisynthetase patients followed at a single Hungarian centre
- Zamora AC; Hoskote SS; Abascal-Bolado B et al. Clinical features and outcomes of interstitial lung disease in anti-Jo-1 positive antisynthetase syndrome. Respir Med. 2016;118:39-45. 10.1016/j.rmed.2016.07.009Fifteen-year cohort of 103 patients identified with anti-Jo-1 positive antisynthetase syndrome and interstitial lung disease
- de Andrade VP; De Souza FHC; Behrens Pinto GL et al. The relevance of anti-Jo-1 autoantibodies in patients with definite dermatomyositis. Adv Rheumatol. 2021;61:12. 10.1186/s42358-021-00171-xRetrospective cohort from 2005 to 2020 of 118 adult patients at a tertiary centre diagnosed with definite dermatomyositis
- Cavagna L; Trallero-Araguás E; Meloni F et al. Influence of Antisynthetase Antibodies Specificities on Antisynthetase Syndrome Clinical Spectrum Time Course. J Clin Med. 2019;8. 10.3390/jcm8112013Retrospective analysis of 828 patients with antisynthetase syndrome from the American and European Network of Antisynthetase Syndrome collaborative cohort
- Noguchi E; Uruha A; Suzuki S et al. Skeletal Muscle Involvement in Antisynthetase Syndrome. JAMA Neurol. 2017;74:992-999. 10.1001/jamaneurol.2017.0934Cohort study collecting muscle biopsy and blood samples from 460 patients with idiopathic inflammatory myositis across regional referral centres in Japan between October 2010 and December 2014
- Sreevilasan SK; Devarasetti P; Narahari NK et al. Clinical profile and treatment outcomes in antisynthetase syndrome: a tertiary centre experience. Rheumatol Adv Pract. 2021;5:ii10-ii18. 10.1093/rap/rkab054Prospective follow-up of 28 patients classified as antisynthetase syndrome by Connors criteria at a tertiary centre over 5 years
- Wang R; Zhao Y; Qi F et al. Analysis of the clinical features of antisynthetase syndrome: a retrospective cohort study in China. Clin Rheumatol. 2023;42:703-709. 10.1007/s10067-022-06404-8Retrospective cohort of 88 patients diagnosed with antisynthetase syndrome at one Chinese hospital between January 2015 and December 2020
- Zhan X; Yan W; Wang Y et al. Clinical features of anti-synthetase syndrome associated interstitial lung disease: a retrospective cohort in China. BMC Pulm Med. 2021;21:57. 10.1186/s12890-021-01399-5Retrospective cohort of 108 consecutive patients with antisynthetase syndrome-associated interstitial lung disease at one Beijing hospital
This page gathers the published research on this subject into one place. The studies behind it were published between 1989 and 2026, and every figure links to the paper it came from. Those studies were peer reviewed. This summary of them was not. Dr. Sarah Luebker is reviewing these pages one at a time and has not reached this one yet, so it carries no medical review date and nothing here is her opinion or her advice to you. Each page gets updated as she reaches it. It is here in the meantime because the science is worth having in one organized place that is easy to find and easy to read. Talk to your own clinician before acting on any of it.