[Note: An article published by members of this team in 1999 suggested that “autoimmunity could explain” FM and/or CFS.]
Autoimmune fatigue syndrome (AIFS) is characterized by chronic nonspecific complaints, consistently positive antinuclear antibodies (ANA), and lack of alternate medical explanations. A newly recognized antibody, named anti-Sa, was detected in approximately 40% of the patients by Western blot (WB) using HeLa extract.
Some patients with AIFS later develop chronic fatigue syndrome (CFS), and most of them are positive for anti-Sa.
On the other hand, Muro et al. reported anti-DFS70 in patients with CFS. Anti-Sa and anti-DFS70 turned out to be same specificities by exchanging studies of blind sera.
The target antigen of anti-DFS70 was identified as lens epithelium derived growth factor/transcription co-activator p75 (LEDGF/p75).
The objectives of this study are to confirm whether the target antigen of anti-Sa is also LEDGF/p75, and to develop ELISA system by using recombinant protein.
Recombinant protein of LEDGF/p75 was purchased from Protein One (Bethesda, MD, USA). We developed an ELISA system to detect anti-LEDGF/p75 by coating this recombinant protein.
226 sera of AIFS patients (including 36 CFS patients) were applied to this ELISA assay and Western immunoblot, and it was revealed that anti-Sa-positive sera defined by WB and sera positive for anti-LEDGF/p75 on ELISA were identical.
Moreover, reactivities of anti-Sa on Western Blot were inhibited by pre-incubating with recombinant LEDGF/p75, and eluted antibodies from the nitrocellulose membrane could react on the ELISA.
These results confirm that the Sa antigen is LEDGF/p75.
The ELISA assay using recombinant LEDGF/p75 could be a promising tool for measuring anti-Sa and consequently for diagnosing CFS.
Source: Autoimmunity, Aug 3, 2009:1. PMID: 19657776, by Kuwabara N, Itoh Y, Igarshi T, Fukunaga Y. Department of Pediatrics, Nippon Medical School, Tokyo, Japan.