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Homogenates of bovine iris were fractionated by gel filtration chromatography, and the column-eluted proteins were probed with pooled sera obtained from patients with pauciarticular juvenile rheumatoid arthritis (JRA). The serum pool prepared from patients with pauciarticular JRA and a history of anterior uveitis, but not from those without the eye disease, contained IgG antibodies which bound a low molecular weight iris antigen (LMW-IA) as measured by a modified ELISA. LMW-IA was protease-sensitive and contained at least four proteins of approximate molecular weights of 16, 13, 9 and 6.5 kD with no uronic acid or carbohydrate. Analysis of individual patient sera for IgG anti-LMW-IA antibody demonstrated that 1/20 (5%) pediatric non-rheumatic disease controls (NRDC), 1/19 (5.3%) non-uveitic pauciarticular JRA patients and 6/21 (28.6%) uveitic pauciarticular JRA patients were positive by ELISA. Levels of anti-LMW-IA antibody did not correlate with serum IgG concentration, the presence of IgG antibody to soluble retinal S antigen (S antigen) or reactivity to the low molecular weight fraction of bovine choroid (LMW-C). Ten of 21 (47.6%) children with pauciarticular JRA and uveitis had serum antibody that reacted with LMW-IA and/or retinal S antigen as compared to 1/20 (5%) NRDC patients and 3/19 (15.8%) patients with pauciarticular JRA uncomplicated by uveitis. Analysis of patient immunoreactivity to proteins of the anterior uveal tract may provide a greater understanding of pathogenic features related to arthritis-associated eye disease.

Sera of 153 children with rheumatic diseases were assayed by an enzyme-linked immunosorbent assay (ELISA) for the presence of antibodies to native (n) and to denatured (d) type II collagen (IIC). Among the study population, antibodies to nIIC were detected in 47% with juvenile rheumatoid arthritis (JRA), 21% with spondyloarthropathies, 37% with other rheumatic diseases, 70% with adult onset rheumatoid arthritis (RA), and in less than 1% of nonrheumatic disease control groups. Antibodies to dIIC were detected in 42% of children with JRA, 41% with spondyloarthropathies, 37% of children with other rheumatic diseases, 67% with adult onset RA, and in less than 6% of nonrheumatic disease control groups. These results indicate that, when compared to nonrheumatic disease control groups, antibodies to both nIIC and dIIC occur significantly more frequently in children with a variety of rheumatic diseases.

The sera of 116 children with a variety of rheumatic diseases were assayed for the presence of antibodies to bovine native type I collagen by an enzyme-linked immunosorbent assay. For comparison, the sera of 69 children without rheumatic diseases, 50 healthy adult blood donors and 23 adults with rheumatoid arthritis (RA) were similarly assayed. Twenty-four % of the 90 children with juvenile rheumatoid arthritis (JRA) had antibodies to native type I collagen. Eleven of 26 (42%) with polyarticular onset, 5 of 53 (9%) with pauciarticular onset and 6 of 11 (55%) with systemic onset JRA had such antibodies. Seven of 10 children with spondyloarthropathies and 8 of 16 children with a variety of connective tissue diseases had antibodies to native type I collagen. Among children with nonrheumatic diseases, 12 of 69 (17%) were anticollagen antibody positive. Anticollagen antibodies were found in 4% of adult blood donors and 70% of adults with RA. Thus, antibodies to native type I collagen occur in a wide variety of childhood rheumatic diseases and their presence is not confined exclusively to rheumatic disorders.

Rheumatic disease sera were examined by a sensitive and specific enzyme linked immunosorbent assay (ELISA) for antibodies to native and to denatured type IV collagen from basement membranes of bovine anterior lens capsules or human placenta. The frequency of antitype IV collagen antibodies depended on the antigen and the disease studied. No controls had human type IV collagen antibodies and only 5.6% had antibody to bovine type IV collagen. Antibody to one or more of our 4 antigens was seen in 20% of children with juvenile rheumatoid arthritis (JRA), 35% of patients with mixed connective tissue disease (MCTD), 40% of those with juvenile dermatomyositis (DM), 52% of adults with rheumatoid arthritis (RA), 56% of patients with scleroderma and 60% of patients with systemic lupus erythematosus (SLE). Antibodies to native human type IV collagen were rare (0-10%) except in SLE (45%). Antibodies to denatured human type IV collagen were commoner in RA, scleroderma and SLE. Antibodies to native bovine type IV collagen occurred in 8-20% of patient sera, and to denatured antigen in 25-26% of scleroderma, MCTD and DM patients. Antibovine type IV collagen activity measured by ELISA could be absorbed from positive sera by preincubation of the sera with bovine type IV collagen but not bovine type I collagen or native human placental type IV collagen, indicating that the antibodies were specific for bovine type IV collagen.