Presence of anti-La(SS-B) is associated with binding to the 13-kD carboxyl terminus of 60-kD Ro(SS-A) in systemic lupus erythematosus.
In systemic lupus erythematosus (SLE) clinical manifestations, autoantibody production, and immunogenetics are inter-related. The ability to study parts of the autoimmune response may allow a more detailed understanding of these relationships. We undertook this study to determine whether the fine specificity of the autoimmune response to 60-kD Ro(SS-A) was related to the presence of other autoantibodies. We screened 74 patients with SLE for antibodies to the carboxyl 13-kD terminal of 60-kD Ro(SS-A) (13 kD). Twenty-five sera had such antibodies. This reactivity was distinguished by the presence of not only anti-Ro(SS-A) but also other antibodies. All nine sera with Ro(SS-A) and La(SS-B) Ouchterlony immunodiffusion precipitins bound 13-kD (p = 0.01), whereas 10 of 11 sera with both anti-Ro(SS-A) and anti-La(SS-B) as determined by immunosorbent assay bound 13-kD (p = 0.002). Inhibition studies demonstrated that antibodies binding the 13-kD fragment bound the 60-kD Ro(SS-A) protein but did not bind the La(SS-B) protein. Thus, anti-La(SS-B) was found in those sera that bound epitopes within the 13-kD carboxyl terminal of 60-kD Ro(SS-A). These data suggest a structural basis by which anti-Ro(SS-A) and anti-La(SS-B) are coupled in SLE.
Dickey
W D
WD
Arthritis and Immunology Programs, Oklahoma Medical Research Foundation, Oklahoma City 73104.
van Egmond
J E
JE
Hardgrave
K L
KL
Harley
J B
JB
Scofield
R H
RH
D000974:Antibodies, Antinuclear / Q000032:analysis* / Q000378:metabolism; D000918:Antibody Specificity; D001324:Autoantigens / Q000276:immunology* / Q000378:metabolism; D001666:Binding Sites, Antibody; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D005779:Immunodiffusion; D008180:Lupus Erythematosus, Systemic / Q000097:blood / Q000276:immunology*; D008297:Male; D010446:Peptide Fragments / Q000276:immunology; D011485:Protein Binding; D020733:RNA, Small Cytoplasmic; D012261:Ribonucleoproteins / Q000276:immunology* / Q000378:metabolism; D000099207:SS-A Antigen
D000974:Antibodies, Antinuclear; D001324:Autoantigens; D010446:Peptide Fragments; D020733:RNA, Small Cytoplasmic; D012261:Ribonucleoproteins; D000099207:SS-A Antigen; C116006:RO60 protein, human; C035356:SS-A antibodies; C035357:SS-B antibodies