Detection by Flow Cytometry of Antibodies against Neutrophil Antigens Expressed by Long Incubation / 대한진단검사의학회지

ABSTRACT

BACKGROUND: We investigated the interactions between spontaneous apoptosis-induced neutrophils and autoantibodies with attention to the reactivities of each autoantibody against intracellular antigenssuch as the antinuclear antibody (ANA) and the anti-neutrophil cytoplasmic antibody (ANCA) and the applicability as a conventional test for autoantibody detection. METHODS: The 127 serum samples from patients with autoimmune disease were mixed with whole blood from healthy donors and incubated for 20 hours. The bound antibody against substrate neutrophils was detected with anti-IgG-FITC by flow cytometry. The results of this anti-long incubated neutrophil antibody (ALINA) testing were compared with ANA, ANCA and clinical manifestations. RESULTS: The positivity rate was significantly higher in the 20 hour incubation than that of a 30 minute incubation (100% and 18%, respectively; P<0.000005). Agreement analyses between ANCA and ALINA (k=0.34) and between ANA and ALINA (k=0.39) were poor. In comparison, among the autoimmune diseases, systemic lupus erythematosus had a significantly higher ALINA positivity rate than did other diseases (P<0.000005). In patients with SLE, higher mean fluorescence intensity was significantly associated with the presence of lupus nephritis (11/12 cases vs. 2/10 cases, P<0.005). CONCLUSIONS: We detected antibodies against neutrophil antigens expressed by long incubation with patient sera. Those detected autoantibodies were significantly associated with SLE, especially lupus nephritis. Therefore, further studies are necessary to devise optimal protocols and to clarify specificities for detected autoantibodies or their target antigens.