Antinucleolar antibodies and their disease association

The prevalence of the antinucleolar antibodies (ANoA) demonstrated by indirect immunofluorescence technique in 1,662 sera of patients with a known or suspected rheumatic disease increased from 1.97% when mouse kidney (MK) was used as substrate to 4.9% when HEp-2 cells were used as substrate. However, an appropriate commercial HEp-2 substrate must be selected in order to increase the sensitivity of ANoA positivity. There were 3 distinct staining patterns of the nucleolar immunofluorescence: homogeneous speckle, and clumpy. Irrespective of the patterns, the most common diagnoses among patients who had ANoA were systemic sclerosis (PSS) and systemic lupus erythematosus (SLE); 36% and 35%, respectively). On the contrary, the incidence of these antibodies in PSS was 41% while it was only 3% in SLE patients. Almost all patients with speckled nucleolar staining had PSS as their underlying disease while most of the patients with homogeneous nucleolar staining had SLE. No distinct correlation between the different nucleolar staining patterns and specific organ involvements in our lupus and PSS patients was found except for the higher frequency of clumpy staining in male scleroderma with no joint involvement. This study demonstrates that: 1) ANoA are uncommon in unselected sera although use of a cell line substrate doubles the rate of positivity; 2) the proper HEp-2 substrate is critical in the detection of ANoA; 3) PSS and SLE are the most frequent diseases associated with ANoA but the frequency of these antibodies in SLE patients was very low.; 4) there are 3 distinct nucleolar staining patterns which may be associated with different rheumatic diseases; and 5) compared with ANoA negative scleroderma, clumpy nucleolar staining had significantly higher incidence in men with no joint involvement but a tendency towards more lung manifestations.