Can anything other than myositis cause elevated jo 1 antibody? Possible false positive? Could I have been wrongly diagnosed w/ rheumatoid arthritis?

Usually not RA. Myositis can be associated with several types of autoantibodies: anti-jo1 antibodies are a type of anti-nuclear antibody. Anti-srp antibodies are mainly associated with, but are not specific for, polymyositis. The ccp antibody is most specific for ra. Keep in mind that certain meds for RA also work in myositis, such as Methotrexate and steroids.