Recombinant 52 kDa Ro(SSA) ELISA detects autoantibodies in Sjögren's syndrome sera that go undetected by conventional serologic assays.
OBJECTIVE
To determine the utility of a recombinant 52 kDa Ro(SSA) ELISA for detecting Ro autoantibodies in Sjögren's syndrome (SS) sera.


METHODS
Several different groups of SS sera previously tested for Ro and La(SSB) autoantibodies in clinical diagnostic labs were tested by ELISA with a recombinant human 52 kDa Ro fusion protein.


RESULTS
Five of 18 primary SS sera (28%) that had undetectable Ro and La autoantibodies by conventional immunodiffusion (ID) or ELISA in clinical diagnostic laboratories had significant reactivity with a recombinant 52 kDa Ro (r52) ELISA. On repeat testing these 5 sera were again negative for Ro and La antibodies by ELISA with purified 60 kDa Ro and La antigens, but 3 of these sera were reactive with r52 by immunoblot, and immunoprecipitated a 52 kDa protein from human cell extracts. Twelve of 12 primary SS sera that had detectable Ro autoantibodies by ID also reacted with the r52 ELISA, whereas none of 11 normal sera and only one of 27 ID-defined Ro negative systemic lupus erythematosus sera did. Eleven of 28 sera from patients with suspected SS were Ro positive by ID and 60 kDa Ro ELISA. All 11 were also Ro positive by the r52 ELISA. Two of the 28 suspected SS sera were Ro positive by the r52 Ro ELISA, but were Ro and La negative by ID and 60 kDa Ro and La ELISA.


CONCLUSIONS
Anti-52 kDa Ro autoantibodies are frequently present in primary SS sera, but may go undetected by commonly used Ro serologic assays. Our r52 ELISA is more sensitive in detecting Ro antibodies in SS than conventional ID and 60 kDA Ro ELISA.
McCauliffe
D P
DP
Department of Dermatology, University of North Carolina, Chapel Hill 27599-7287, USA.
Wang
L
L
Satoh
M
M
Reeves
W H
WH
Small
D
D
D000918:Antibody Specificity; D001323:Autoantibodies / Q000097:blood* / Q000276:immunology; D001324:Autoantigens / Q000235:genetics / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D006801:Humans; D015151:Immunoblotting; D011233:Precipitin Tests; D020733:RNA, Small Cytoplasmic; D011994:Recombinant Proteins; D012261:Ribonucleoproteins / Q000235:genetics / Q000276:immunology*; D012680:Sensitivity and Specificity; D012859:Sjogren's Syndrome / Q000097:blood* / Q000276:immunology*; D000099207:SS-A Antigen
D001323:Autoantibodies; D001324:Autoantigens; D020733:RNA, Small Cytoplasmic; D011994:Recombinant Proteins; D012261:Ribonucleoproteins; D000099207:SS-A Antigen; C116006:RO60 protein, human