Occurrence of autoantibodies directed against myeloperoxidase and elastase in patients treated with hydralazine and presenting with glomerulonephritis.

We have undertaken an investigation retrospectively of 21 patients with positive antinuclear antibodies, who had been on hydralazine treatment and developed a glomerulonephritis. Four patients had circulating antimyeloperoxidase (MPO) and two of them were concluded to have a hydralazine-induced glomerulonephritis, corresponding to a frequency of 10%. These two patients had antibodies of IgG and IgM class directed against myeloperoxidase (MPO), and also antibodies against elastase. These two patients had also a biopsy proven extracapillary glomerulonephritis with focal segmental necrosis. Antibodies against elastase were furthermore seen in three patients with proliferative glomerulonephritis and in one patient with membranoproliferative glomerulonephritis. This study confirms an association between circulating anti-MPO and a histopathological picture compatible with extracapillary proliferation and focal segmental necrosis. From a clinical, histopathological and serological point of view it can be concluded that in two patients the glomerulonephritis was associated with antibody evidence of an autoimmune side effect.