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Rheumatoid factor
| • | most RF’s are IgM directed against the Fc portion of IgG |
| • | high titers tend to correlate with severe disease |
| • | but not useful to assess disease activity (ESR is better) |
Scl 70 antibodies
| • | diffuse scleroderma (specific but not sensitive for); incidence 10-20% |
| • | = enzyme topoisomerase I |
Myositis specific antibodies
Jo1
| • | directed against histydyl t-RNA synthetase |
| • | detected in a small number of patients with dermatomyositis (and polymyositis) |
| • | presence suggests aggressive disease, including interstitial lung disease |
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