Antibodies to the lens and cornea in anti-DFS70-positive subjects

Autoantibodies against DFS70 (dense fine speckles 70) antigen have recently been identified among antinuclear antibodies (ANA) in patients with various inflammatory diseases and in patients with different types of cancer. These antibodies are recognized using indirect immunofluorescence (IIF) on HEp-2 cells, by a fine speckled nuclear staining in interphase HEp-2 cells and a positive reaction in the chromosome region of mitotic cells. Given that the DFS70 protein is also known as the lens epithelium-derived growth factor, this study was performed with two objectives: (a) to assess the prevalence of these antibodies in patients sent for ANA testing and in 334 patients with different types of neoplasia and (b) to determine whether the lens tissue was a suitable substrate for the detection of antibodies specific to lens proteins. During routine workup for ANA detection by the IIF method, we found 172 DFS70-positive sera among 21,516 consecutive samples (prevalence, 0.8%). In the group of patients with neoplastic disease, 6 of 334 (1.8%) were anti-DFS70-positive. DFS70-positive sera were then assayed by the IIF method on cryostatic sections of mouse eye at a dilution of 1:40 with an anti-human IgG conjugate. Among the 172 DFS70-positive samples detected by the ANA screening, 32 (19%) were strongly reactive against the reticular fibers of the lens; 8 (5%) were positive only to the corneal epithelium (nuclear negative); 5 (3%) were positive both for the cornea and the lens fibers; 13 (7%) stained only the nuclei of lens and cornea cells, and 4 (2%) were positive against the ciliary muscle. Among the patients with neoplastic diseases, only one with lung cancer reacted weakly with the reticular fibers of the lens. Sera from 20 healthy blood donors were negative. In this preliminary study, we have shown that the prevalence of anti-DFS70 antibodies is much lower than previously reported, both in patients screened for ANA and in patients with cancer. We have also seen that some DFS70-positive sera have antibodies that recognize antigens of the lens. Further studies are needed to investigate the fine specificity and the possible significance of these new autoantibodies.