MPO and infectious disease: Many reports have found that ANCA positivity associated with infectious diseases can present as double ANCA positivity (high PR3, low MPO titer), accompanied by antinuclear antibody, anticardiolipin antibody, high globulin, anti-β2GPI antibody, and complement consumption.[19] Endocarditis with similar clinical manifestations to AAV is more common with PR3-ANCA, and other non-organ-specific autoantibodies (such as antinuclear antibodies, etc) may also be present.[20]