Some autoantibodies to Ro/SS-A and La/SS-B are antiidiotypes to anti-double-stranded DNA.
OBJECTIVE
To determine the relationship of anti-Ro/SS-A and anti-La/SS-B antibodies to anti-double- stranded DNA (anti-dsDNA) in sera from patients with systemic lupus erythematosus.


METHODS
Sera with anti-Ro/SS-A alone (n = 5) or those with anti-Ro/SS-A and anti-La/SS-B (n = 7) were absorbed with purified Ro/SS-A and La/SS-B, respectively. The absorbed sera were then tested for reactivity with MOLT-4 extract by Western blot and dsDNA by enzyme-linked immunosorbent assay (ELISA). With selected sera, anti-dsDNA was isolated on DNA cellulose columns and anti-Ro/SS-A and anti-La/SS-B were isolated on antigen-affinity columns. Reactivity between anti-dsDNA and autologous anti-Ro/SS-A or anti-La/SS-B, as well as inhibition by cognate antigens, was studied.


RESULTS
After absorption, all sera showed reactivity with small nuclear RNP A and D bands in Western blots, and some showed reactivity with dsDNA by ELISA. Anti-dsDNA populations (n = 4) were purified on dsDNA cellulose columns. Anti-Ro/SS-A (n = 1) and anti-La/SS-B (n = 3) were affinity purified from the same sera as the anti-dsDNA. In all cases, anti-dsDNA bound autologous anti-Ro/SS-A and anti-La/SS-B much more strongly than it bound normal pooled IgG. Moreover, dsDNA, but not RNA, blocked these interactions. In addition, Ro/SS-A blocked anti-Ro/SS-A and La/SS-B blocked anti-La/SS-B in these same interactions.


CONCLUSIONS
In sera with anti-Ro/SS-A and anti- La/SS-B, there are subpopulations of these antibodies that bind and mask anti-dsDNA. We hypothesize that these anti-Ro/SS-A and anti-La/SS-B antibodies are antiidiotypes to idiotypes on anti-dsDNA and that they both mask and down-regulate these anti-dsDNA antibodies.
Zhang
W
W
Oklahoma Medical Research Foundation and the College of Medicine, The University of Oklahoma Health Sciences Center Oklahoma City, 73104, USA.
Reichlin
M
M
D000888:Antibodies, Anti-Idiotypic / Q000276:immunology*; D000974:Antibodies, Antinuclear / Q000276:immunology*; D001323:Autoantibodies / Q000276:immunology*; D015153:Blotting, Western; D002482:Cellulose; D004247:DNA / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology / Q000302:isolation & purification; D007163:Immunosorbent Techniques; D008180:Lupus Erythematosus, Systemic / Q000097:blood / Q000276:immunology; D012859:Sjogren's Syndrome / Q000097:blood / Q000276:immunology
D000888:Antibodies, Anti-Idiotypic; D000974:Antibodies, Antinuclear; D001323:Autoantibodies; D007074:Immunoglobulin G; C035356:SS-A antibodies; C035357:SS-B antibodies; D002482:Cellulose; D004247:DNA