Background/Purpose:  A Mixed Speckled/Homogeneous (MS/H) pattern is the single most common ANA pattern identified in our community hospital patient population, often in very high titers, and has been associated with a “Dense Fine Speckled” anti-DFS70 ENA specificity. The IFA pattern on a Hep-2 cell substrate is that of dense, finely speckled interphase nuclei with strongly fluorescent mitotic chromosomes—ICAP pattern #2. Patients with a DFS70 positive MS/H ANA are reported to rarely develop systemic autoimmune rheumatic disease (SARD), especially in the absence of significant clinical findings or other significant ENA specificities, prompting suggestion that an isolated DFS70-specific ANA may be an exclusionary finding for SARD.

Methods: All ordered ANAs are tested using Euroimmun Hep-2 substrate slides. All MS/H ANA pattern results are reported as possibly DFS70-related, with ENA follow-up analysis recommended. ENA profiling uses the Euroimmun Immunoblot ANA Profile 3-plus DFS70 kit which includes a total of 15 separate ENA specificities. Chart reviews were done on these patients to determine if the isolated DFS70 pattern was useful as a rule-out for SARDS.

Results: 2,383 patient samples tested for ANA in a 4-month period showed 632 (27%) to have an MS/H ANA pattern. ENA profiling of these 632 MS/H ANA’s showed: · 260 (41%) of MS/H ANA’s positive for anti-DFS70, 73% of these an isolated anti-DFS70. · 71 (27%) of DFS70 ANA’s showed an additional positive or borderline reaction to other ENA  specificities. · 353 (59%) of MS/H ANA’s were negative or showed only borderline (3%) reactivity for anti- DFS70; · 263 (75%) of DFS70-negative MS/H ANA’s were also ENA profile negative; while the remainder showed varied presence of other ENA specificities. Ongoing chart reviews of patients positive for an isolated anti-DFS70 ANA affirms that evidence of SARD is rare in patients with isolated anti-DFS70 patients in the absence of clinical evidence or other ENA specificities. The presence other ENA specificities at a significant level has clinical relevance specific to those antibodies.

Conclusion: Recognition of an MS/H, Dense Fine-speckled, ICAP AC-2 ANA pattern should be a routine ANA testing service. A mitotic-rich Hep-2 cell substrate is essential for recognition of this and of varied cell-cycle ANA patterns. Recognition of an isolated DFS70 ANA specificity enables reassurance of ANA-positive patients who would otherwise be referred for more extensive testing and monitoring for the presence or development of SARD.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/importance-of-mixed-speckled-homogeneous-dfs70-ana-patterns/