[Anti-nuclear antibodies (ANA) in sera of aged subjects, with special reference to two cases with high titers of anti-centromere antibody (ACA)].

Recently, tissue cultured cells including HEp-2 cell have widely been used as the substrates for detecting autoantibody to nuclear antigen (ANA) by indirect immunofluorescence method. In this study, sera from aged subjects ranging from 70 to 92 years of age were examined for the presence of anti-nuclear antibodies by the indirect immunofluorescence method. Positive reactions were obtained in 51 of 269(23.3%) aged subjects and positive fluorescent staining patterns of ANA were speckled in 40, homogeneous in one, speckled + homogeneous in 4, nucleolar in one and discrete speckled in two sera respectively. The titers of ANA were low ranging between 1:20 and 1:320, however two cases showed discrete speckled staining with high titers at 1:2,560. Antibody to extractable nuclear antigen (ENA) was not detected by precipitation test in aged subjects. The aged individuals with low ANA titers did not show any symptoms suggestive of collagen diseases. In two patients whose sera contained high titers of anti-centromere antibody (ACA), one was suspected to be accompanied by primary biliary cirrhosis (PBC), however the other showed neither any other abnormal symptoms nor abnormal laboratory data. Our results indicated that low titer ANA other than ACA might not be clinically significant in aged subjects.