Background: Sera of patients with atopic dermatitis (AD) were found to have
autoantibodies that reacted with tissue culture cell substrates in immunoh
istochemistry to display a characteristic pattern of nuclear distribution o
f dense fine speckles. The sera also recognized a 70-kd protein on Western
immunoblots, and the antigen was termed dense fine speckles 70 kd (DSF70).
Objective: Because spontaneously occurring autoantibodies could be immune r
esponses to proteins that might be participating in the disease process, it
was of interest to identify the antigens driving the autoimmune antibody r
Methods: A serum containing high-titer antibodies to DFS70 was used to immu
noscreen a complementary (c)DNA expression library to isolate cDNA encoding
the antigen. After the cDNA was isolated, this was used to express recombi
nant protein to determine the prevalence of antibody in AD and other condit
Results: Thirty percent of patients with AD were found to have antibody to
recombinant DFS70 in Western immunoblots. Sixteen percent of patients with
asthma and 9% of patients with interstitial cystitis had antibodies of the
same specificities. The cDNA encoding DFS70 was identical to a transcriptio
n coactivator called p75, which had been shown to be required for RNA polym
erase II-dependent transcription. Another important finding was that IgE an
tibodies to DFS70 were also present in AD sera.
Conclusion: It is suggested that a common basis for the presence of autoant
ibodies to DFS70 might be related to AD in asthma, interstitial cystitis, a
nd other conditions. A possible role of this antigen-antibody system in pat
hogenesis remains to be demonstrated, but it appears to be a marker for a s
ubset of patients with AD.