Figure 1.

Anti-RNAP III antibodies by immunoprecipitation, immunofluorescence, and ELISA. A). Immunoprecipitation using ³⁵S-methionine labeled K562 cell extract. ³⁵S-methionine labeled K562 cell extract was immunoprecipitated by serum samples from patients with anti-RNA polymerase I/III, who had atypical clinical presentations (Table 1) and controls. RNAPs, RNA polymerases; I, II, III, two largest subunits of RNA polymerase I, II, and III, respectively; lane I, II, III, a reference serum with anti-RNAP I/II/III; lane I, III, a reference serum with anti-RNAP I/III; 1 to 6, IP with sera from cases 1 to 6; NHS, normal human serum; positions of molecular weight markers are also indicated. B). Immunofluorescence. HEp-2 ANA slide was stained with sera from cases 1 to 6 (Table 1) at 1:80 dilutions. C). Anti-RNAP III levels by ELISA. Sera from 21 cases with anti-RNAP I/III were tested by ELISA. Six cases of atypical presentation (Table 1) and 15 cases of typical presentation of SSc are shown. P = 0.04 by Mann-Whitney; closed circle, SSc; open circles, atypical cases in Table 1. D). Anti-RNAP III levels over time. Sera from cases 2, 4 and 6 over time were tested by anti-RNAP III ELISA. Time points of onset of sclerodermatous skin change (black arrowhead) or Raynaud's phenomenon (white arrowhead) are indicated. A cut-off (20 units) is shown as shaded area.