DETECTION OF ANTINEUTROPHIL AUTOANTIBODIES BY FLOW-CYTOMETRY - USE OFUNFIXED NEUTROPHILS AS ANTIGENIC TARGETS

Antineutrophil antibodies may be found in the sera of patients with ch ronic neutropenia as well as in the sera of a variety of patients with neutropenia and associated autoimmune or infectious disorders. We eva luated an immunofluorescent flow cytometric technique for the measurem ent of antineutrophil antibodies in serum. Sera from patients with sus pected immune neutropenia were studied and compared with a group of se ra from normal healthy individuals, as well as with sera from patients with rheumatoid arthritis and systemic lupus erythematosus. Of 159 pa tients with suspected immune neutropenia and a variety of associated c linical disorders, 59 (37%) were found to have evidence for enhanced b inding of IgG to normal target neutrophils, interpreted as positive fo r antineutrophil antibodies. Whereas 0/37 nonneutropenic patients with typical RA had positive results, 51/244 (21%) of sera from nonneutrop enic patients with SLE or other collagen vascular disorders showed enh anced IgG binding to neutrophils. Living neutrophils were used to stud y the effects of cellular activation, and increased antibody binding w as observed with certain sera that contained IgG directed against acti vation-dependent antigens. We found that, under controlled conditions, flow cytometry can be reliably used to detect antineutrophil autoanti bodies, with unfixed, living neutrophils as antigenic targets. (C) 199 3 Wiley-Liss, Inc.