Serum samples of patients with rheumatoid arthritis contain a specific autoantibody to "denatured" aldolase A in the osteoblast-like cell line, MG-63.
OBJECTIVE
To identify rheumatoid arthritis (RA) specific autoantibody and its antigen in the human osteoblast-like cell line, MG-63.


METHODS
MG-63 cell extract was subjected to western blotting by using RA and normal serum samples as probes. The autoantigen was purified and its N-terminal sequence was determined by automated Edman degradation. The reactivity of denatured aldolase A was evaluated by immunoblotting. Screening by enzyme linked immunosorbent assay (ELISA) using the autoantibody was performed.


RESULTS
40 kDa protein was found only in the RA serum samples and it was identified as aldolase A. A polyclonal antibody for rabbit muscle aldolase A bound to the 40 kDa protein and reacted in preference with the denatured enzyme. Using ELISA for denatured rabbit aldolase A, the autoantibody was found in approximately 10% of RA patients, whereas it was not found in the other arthropathy and healthy adults.


CONCLUSIONS
This 40 kDa anti-aldolase A autoantibody, which was identified only in serum samples of RA patients with severe bone erosion, could be related to a certain event that induces RA specific joint destructions.
Ukaji
F
F
Department of Laboratory and Molecular Medicine, Kagoshima University, School of Medicine, Japan.
Kitajima
I
I
Kubo
T
T
Shimizu
C
C
Nakajima
T
T
Maruyama
I
I
D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000201:enzymology / Q000276:immunology*; D001323:Autoantibodies / Q000032:analysis / Q000097:blood*; D015153:Blotting, Western; D002460:Cell Line; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005634:Fructose-Bisphosphate Aldolase / Q000276:immunology*; D006801:Humans; D015151:Immunoblotting; D007527:Isoenzymes / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D010006:Osteoblasts / Q000201:enzymology / Q000276:immunology*; D011489:Protein Denaturation
D001323:Autoantibodies; D007527:Isoenzymes; D005634:Fructose-Bisphosphate Aldolase