Fig. 1.

Detection of the dense fine speckled (DFS) immunofluorescent pattern using human sera. Representative human sera displaying the characteristic DFS nuclear pattern in HEp-2-ANA slides, visualized by IIF microscopy using FITC-labeled secondary antibodies, are shown in the first five panels from left to right. Corresponding DAPI staining is shown in black and white for better visualization of chromatin. Note that the mitotic chromatin is brightly stained with the positive control sera and with sera HI-829, OB-041, and RA-909, but the DFS staining pattern produced by serum DM-119 was atypical since the mitotic chromatin was stained only at the edges. Serum DM-041 in the far right panel displays the characteristic NFS pattern (unrelated to the DFS pattern). Yellow arrows point to the negative staining of mitotic chromatin