This report elucidates a new cross-reactive intracellular target of anti-ds
DNA antibodies. Previous experiments have demonstrated that some anti-dsDNA
antibodies penetrate cells grown in tissue culture and all inhibit in vitr
o translation. Data implicate a crossreactive antigen directly involved in
protein synthesis: elongation factor-2 (EF-2). EF-2 was identified by N-ter
minal sequencing of a band identified with an antibody to the ribosomal pro
tein S1 from Leuconostoc lactis in Western blot assay. Anti-DNA antibodies
bind directly to purified EF-2 from bovine liver in dot blot assays. Anti-d
sDNA antibodies were shown to inhibit in vitro translation. This inhibiting
effect of anti-dsDNA antibodies was partially restored by EF-2 and abrogat
ed by dsDNA, suggesting this cross-reactive specificity. These data demonst
rate a cross-reaction between anti-dsDNA antibodies and EF-2 which may lead
to cellular dysfunction, as evidenced by inhibition of protein synthesis,
and provide a direct pathogenic role for cell penetrating anti-dsDNA antibo
dies. (C) 2000 Academic Press.