Journal of Experimental Medicine, Vol 165, 1172-1187, Copyright © 1987 by Rockefeller University Press
Description and partial characterization of a nucleolar RNA-associated autoantigen defined by a human monoclonal antibody
N Chiorazzi and WH Reeves
B lymphocytes from a patient with systemic lupus erythematosus (SLE) and
several circulating autoantibodies (including antinucleolar antibodies)
were immortalized by fusion with a hypoxanthine/guanine phosphoribosyl
transferase (HGPRT)-deficient human B cell line. Multiple human monoclonal
antibodies (mAb) were obtained which, in solid-phase enzyme immunoassay,
were reactive with DNA. One mAb was of special interest because it reacted
strongly with both single-stranded DNA and an extractable nuclear antigen
found in rabbit thymus extract (RTE). In an immunofluorescent assay using
fixed human cells, the latter mAb also bound predominantly to cell
nucleoli. A combination of enzyme digestion and metabolic inhibitor studies
of the target cells in this immunofluorescent assay suggested that the
antigen(s) bound by the mAb was an RNA-associated protein or a
ribonucleoprotein that is distinct from intact RNA polymerase I and not
associated with the transcriptional units of the nucleolus. In other
experiments, using fractions of RTE isolated by ion-exchange
chromatography, the antigens bound by the mAb were shown to be highly
negatively charged molecules. Immunoprecipitation and SDS-PAGE analyses of
labeled cell extracts bound by the mAb revealed a doublet of 17 and 18 kD.
Since the original patient's serum autoantibodies also bound to both an
RNase-sensitive, acidic, extractable nuclear antigen and to nucleoli, and
immunoprecipitated proteins of similar molecular masses in SDS-PAGE, it
appears that the described mAb is a product of an immortalized
autoantibody-producing B cell clone from the SLE patient's peripheral
blood. This mAb probably defines a novel RNA-associated autoantigen
residing predominantly in the nucleolus or, less likely, a variant of
either RNA polymerase I or the ribosomal autoantigens (P proteins).
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Facebook 
Reddit 
Technorati 
Twitter What's this?
