Symptomatology and diagnosis in connective tissue disease. Antibodies to extractable ribonucleoprotein in 123 patients reacting with cell nuclei in the immunofluorescence test.

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Sera with an antinuclear immunofluorescence titre of 1/000 were taken consecutively from the diagnostic routine flow and examined for agglutinating antibodies against desoxyribonucleic acid (DNA) and extractable nuclear antigens (ENA). Passive haemagglutination tests with antigen-coated tanned erythrocytes were used and the specificity of the reactions was corroborated by testing against enzyme-treated cells. After the exclusion of the DNA-reacting 15%, three major groups and one minor could be distinguished on a serological basis. The largest group (41%) contained cases with a speckled immunofluorescence pattern and a RNase-trypsin sensitive agglutination reaction with ENA coated cells (sRNP). Nearly all cases of mixed connective tissue disease and scleroderma fell into this group which also contained 44% of the SLE cases. Symptomatically the group was characterized by remarkably high incidences of Raynaud's syndrome and myositis. The major group next in size comprised cases with a homogeneous immunofluorescence pattern but no reaction against DNA or ENA. Half of the cases within this group had the diagnosis SLE; they also constituted 42% of all SLE cases. The only other diagnosis of significant frequency within the group was unspecified collagenosis (23%). The symptomatology of the group was rather uncharacteristic, with the exception of the low incidence of Raynaud's syndrome. The third major group comprised cases with a speckled immunofluorescence pattern but no agglutination reaction against ENA or DNA. This group had a very high incidence of rheumatoid factor and also the highest incidence of visceral lesions among the groups. Yet the group contained only a small proportion (14%) of the SLE cases and the rheumatoid arthritis cases were about equally shared between this and the first group. The most common diagnosis in the group was unspecified collagenosis (40%). A fourth, small but homogeneous group contained cases with a speckled immunofluorescence pattern and a reaction with Sm antigen, i.e. an enzyme-resistant agglutination reaction with ENA. Six cases in this group had the diagnosis SLE. No diagnosis was available in two cases.