Figure 3.

Autoantibodies to small nuclear ribonucleoproteins by immunoprecipitation. Immunoprecipitation by anti-small nuclear ribonucleoprotein immunoprecipitation-positive sera (lanes 1 to 7, all seven sera from the anti-cytomegalovirus (CMV) IgM(+) group; lanes 8 to 13, six randomly selected sera from the 12 in the anti-CMV IgM(-)IgG(+) group) and a normal human serum (NHS) are shown. Positions of UsnRNP components A, B'/B, C, D1/D2/D3, E/F, G, U5–200 k doublet, and 60 k Ro, and molecular weights (kDa) are indicated. White arrowheads, U5–200 k.