Detection of anti-neutrophil cytoplasmic autoantibodies using the promyelocytic HL-60 cell-line

IgG autoantibodies against antigen in the cytoplasm of cells of the neutrophil-monocyte cell lineage have been found in the sera of patients with Wegener's granulomatosis (WG). The indirect immunofluorescence test (IFT) is proving to be a valuable screening test for these antibodies, but obtaining neutrophils for substrate is time-consuming, and interpretation of the fluorescence patterns in ethanol-fixed cells requires considerable experience. We report an improved IFT using HL-60 cells as substrate. The myeloid reactivity of HL-60 cells was characterized and compared to that of neutrophils, with and without prior ethanol fixation. In contrast to neutrophils, myeloperoxidase (MPO) was more completely extracted from HL-60 cells by prior ethanol fixation, eliminating the confusion inherent in trying to distinguish anti-MPO antibodies from Wegener's granulomatosis associated anti-neutrophil cytoplasmic autoantibodies (WG-ANCA) in the IFT. The WG-ANCA reactivity remained intact with ethanol fixation, producing a distinct crescent and half-moon pattern of specific immunofluorescence. This WG-ANCA positive pattern was found in 25 sera from 11 WG patients and was absent in over 1200 control sera from patients referred for autoantibody testing.