ABSTRACT
Autoantibodies against nuclear proteins are not always but rather frequently present
in sera of patients with primary biliary cirrhosis (PBC). The specificity and diagnostic
value of these autoantibodies for PBC have only recently become clear through cloning
of the cDNA of some of the corresponding autoantigens which allowed the establishment
of immunological assays with recombinant autoantigens expressed in E. coli and eukaryotic
cells. In this report we summarize primarily the knowledge on the structure and putative
function of two nuclear autoantigens, the Sp100 and PML proteins, which are present
in so-called nuclear dots (NDs) and against which autoantibodies are present in a
subpopulation of PBC patients. Furthermore, the type of autoimmune response (epitope
specificity and immunoglobulin class) against both the Sp100 and PML proteins and
the specificity of the anti-Sp100 and anti-PML autoantibodies for PBC patients and
patients with other autoimmune diseases is reviewed. Current knowledge clearly indicates
that determination of anti-Sp100 and anti-PML autoantibodies substantially improves
diagnosis of PBC as these autoantibodies are highly specific for this disease even
when autoantibodies against mitochondrial antigens, a hallmark of most PBC patients,
are not found. The type of autoimmune response against the Sp100 and PML proteins
also provides some clues about possible mechanisms which lead to autoantigenicity
of both proteins.
KEY WORDS
nuclear dots - Sp100 - PML - autoantigens - PBC - interferon - autoimmunity
