Background/Purpose: The dense fine speckled (DFS) pattern in IIF-ANA on HEp-2 cell is perhaps the most frequently observed pattern in most clinical laboratories. The DFS70 or lens epithelium-derived growth factor p75 (LEDGFp75) is the known corresponding antigen to the DFS pattern. Identification of this antibody can be an evidence to exclude the presence of systemic autoimmune rheumatic diseases (SARD), however this correlation requires more definite clinical correlation. The aim of our study is to confirm the presence of anti-DFS70 in specimens showing DFS pattern by western blot (WB) and enzyme immunoassay (EIA). Also the association between the anti-DFS70 and SARD or certain clinical conditions is discussed.

Methods: A total of 227 serum specimens showing DFS (n=180, only DFS (158) and DFS+other (22)) and homogeneous (H) (n=47, only H (33) and H+other (14)) patterns in IIF-ANA screening test were included. All specimens were tested twice by IIF-ANA and the results interpreted by two separate expert specialists of Laboratory Medicine. The cases with discrepant results between the two interpreters were excluded. The results of first and second test results of IIF-ANA were compared. In-house WB was performed using deriving cell lysate from cultured HeLa cells. Detection of anti-DFS70 IgG was done using a commercial EIA kit. The clinical information regarding disease status or the presence of SARD of subjects was obtained from retrospective review of individual medical records.

Results: Forty four cases (19.4%) showed discrepant reading in their repeated IIF-ANA test results. The majority of those results included the following: 19 cases (DFS pattern in first test result then interpreted as another in second test result, especially 14 cases as H pattern), 9 cases (from DFS pattern to negative), and 13 cases (changed with only combined pattern). There were also 17 other cases in which the results were complex and indeterminable. Among 155 cases with DFS pattern in the second test results of IIF-ANA, 134 cases (86.5%) were positive by WB and 114 cases (73.5%) positive by EIA. WB had covered all cases in which this autoantibody was detected. The number of cases detected of anti-DFS70 are divided into three groups which are as follows; 114 (73.5%) in WB+/EIA+, 20 in WB+/EIA-, and 21 in WB-/EIA-. There was no case which showed only EIA positivity. More than half of the patients from each group were referred to the department of dermatology, where many were given their diagnoses of androgenic alopecia. SARD patients with DFS pattern were 1 (SLE) in WB+/EIA+, 3 (1 SSc, 2 RA) in WB+/EIA-, and 1 (RA) in WB-/EIA-.

Conclusion: The prevalence of SARD (2.2%) was very low in this study of randomly selected 180 DFS and 47 H pattern cases. This result suggests the utility of anti-DFS70 to exclude SARD when detected. DFS pattern can also provide a clue to exclude SARD based on the results that anti-DFS70 was detected in 86.5% of cases with DFS pattern given that IIF-ANA tests were conducted twice and interpreted carefully by two separate specialists. However presence of a confusing pattern or the absence of monospecific anti-DFS70, additional tests are necessary to rule out the diagnosis of SARD.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/clinical-significance-of-anti-dense-fine-speckled-70-and-dense-fine-speckled-pattern-in-diagnosis-of-systemic-autoimmune-rheumatic-disease/