Studies on associations of antinuclear antibodies with antibodies to an uveitogenic peptide of retinal S antigen in children with uveitis.

OBJECTIVE: To determine if, in children with uveitis, antinuclear antibodies (ANA) are associated with antibodies to an uveitogenic peptide of a soluble retinal antigen and to the homologous nuclear antigen, histone 3 (H3). ANA occur in most children with juvenile rheumatoid arthritis (JRA) and associated uveitis. An uveitogenic segment of retinal soluble antigen (S antigen peptide) is homologous with a similarly uveitogenic peptide of H3. We investigated a possible association between ANA positivity, antibodies to H3, and antibodies to the uveitogenic S antigen peptide. METHODS: The sera of 31 children with uveitis (20 of whom had associated JRA) were tested for the presence of ANA by indirect immunofluorescence. Antibodies to H3 and to an uveitogenic peptide of S antigen (an 18 mer segment having the amino acid sequence DTNLASSTIIKEGIDKTV) were measured by enzyme immunoassay. RESULTS: 19 of 20 children (95%) with JRA and associated uveitis and none of 11 with uveitis not associated with JRA had positive tests for ANA (X2 = 14.97; p < 0.00001). 16 of 19 ANA positive sera from subjects with JRA (84%) displayed reactivity with the chromosomal regions of metaphase cells. 9 of 20 patients with JRA with uveitis (45%) and 2 of 11 patients (18%) with uveitis not associated with JRA had antibodies to H3. Two uveitic patients with JRA (10%) and 2 non-JRA patients with uveitis (18%) reacted with S antigen peptide. Antibodies to H3 occurred significantly more frequently in children with uveitis than in all adult control subjects (X2 = 12.98; p = 0.003) and in adults with uveitis (X2 = 5.62; p = 0.022). CONCLUSION: Humoral immune responses to the uveitogenic peptide of S antigen and the homologous H3 antigen appear not to be uniquely important in the immunopathology of uveitis associated with JRA. Antibodies to isolated H3 do not exclusively account for ANA positivity in the uveitic patient with JRA. A unique immunopathogenic mechanism for the development of uveitis associated with JRA is suggested by the observations that (1) children with uveitis associated with JRA are more likely to be ANA positive than children with uveitis not associated with JRA, and (2) children with uveitis associated with JRA are significantly more likely to be ANA positive and to have antibodies to H3 than adults with uveitis.

Antinuclear antibodies in children with localized scleroderma.

OBJECTIVE: To determine the prevalence and antigenic specificities of antinuclear antibodies (ANA) in children with localized scleroderma. METHODS: The ANA profiles of 27 children with localized scleroderma were determined. The study group comprised 21 children with linear scleroderma, 5 with morphea, and 1 with combined linear scleroderma and morphea. Sera were evaluated for the presence of ANA by indirect immunofluorescence and for reactivity with specific nuclear antigens by ELISA and immunoblotting. RESULTS: Seventeen patients (63%) had positive tests for ANA. Of these sera 10 displayed a finely speckled pattern, 5 a combined nucleolar and finely speckled nuclear pattern, and 2 a nucleolar pattern only. Fourteen of 21 (67%) with linear scleroderma were ANA positive. Three of 5 patients with morphea (60%) had ANA. The 1 patient with both linear scleroderma and morphea was ANA negative. Fifteen sera (56%) contained antibodies to denatured DNA (dDNA). Eleven sera (41%) had antibodies to one or more high mobility group (HMG) proteins, 4 (15%) reacted with one or more histones and 1 serum (4%) reacted with topoisomerase I (Sc1-70). CONCLUSION: ANA are present in most children with localized scleroderma and frequently have specificity for dDNA and HMG proteins. Children with localized scleroderma, like patients with systemic sclerosis (SSc), commonly have ANA and antibodies to dDNA. Unlike patients with SSc, however, childhood localized scleroderma is uncommonly associated with antibodies to certain specific nuclear and nucleolar constituents that typically occur in association with SSc.

The binding of native DNA to the collagen-like segment of Clq.

Our study was undertaken to determine if native DNA (dsDNA), which is known to bind to collagen, also binds to the collagen-like segment of Clq (CLS). Three methods were employed to demonstrate the binding of dsDNA to CLS: (1) Six human sera and a mouse monoclonal antibody to dsDNA were employed in an enzyme linked immunosorbent assay to detect CLS bound dsDNA. When applied to CLS bound dsDNA, sera with antibodies to dsDNA and monoclonal antibody to DNA yielded mean OD values of greater than or equal to 0.6, significantly higher than those values obtained from control experiments (mean OD less than or equal to 0.2, p less than or equal to 0.003). (2) In a solid phase immunoassay radiolabelled DNA (3H DNA) was exposed to increasing amounts of solid phase adherent CLS. The binding of 3H DNA to the solid phase was substantially greater (more than a 30-fold increase) when the solid phase had been precoated with CLS. (3) dsDNA binding to CLS was demonstrated further by incubating electrophoretically resolved CLS with dsDNA and localizing the bound dsDNA by ethidium bromide staining. Our results indicate the dsDNA binds to CLS. Since CLS is the binding site for Clr and then Clr2Cls2, molecules which bind to CLS, such as dsDNA, could be important factors affecting Cl activation.

The binding of dsDNA and ssDNA to human types I, II and IV collagens.

Our study was undertaken to determine if dsDNA and ssDNA, which are known to bind to bovine collagen and to glomerular basement membrane, also bind to purified human types I, II and IV collagens. Four human sera with antibodies to dsDNA and 4 human sera with antibodies to ssDNA, when employed in an enzyme linked immunosorbent assay, detected DNA binding to the solid phase only when the solid phase had been precoated with collagen. Mean optical densities (OD) of .978, 1.062 and 1.033 for dsDNA binding to types I, II and IV collagens, respectively, were substantially higher than the mean OD value of .177 obtained when dsDNA was applied to the noncollagen coated solid phase. Similarly, mean OD values of .664, .526 and .902 for ssDNA binding to types I, II and IV collagens, respectively, were higher than the mean OD value of .147 obtained when ssDNA was applied to the noncollagen coated solid phase. The affinity of DNA for collagen could be an important factor contributing to the localization of DNA-anti-DNA complexes in target tissues.