NAA10 and systemic lupus erythematosus: Serum anti-MAA antibody positivity is low (less than 15%) among healthy controls and spondyloarthrotpathy (SpA) patients, but found in higher levels in other arthritis patients, especially those with systemic lupus erythematosus (SLE) and OA, which limits its utility as a possible diagnostic tool for seronegative RA (30, 33, 39).