Symptomatology and Diagnosis in Connective Tissue Disease: II. Evaluations and Follow-up Examinations in Consequence of a Speckled Antinuclear Immunofluorescence Pattern

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Abstract
Antibodies to soluble ribonucleoprotein (sRNP) are by definition a prerequisite for the diagnosis mixed connective tissue disease (MCTD). They are also found in 30-40 % of other rheumatic conditions with a high titred speckled IFL reaction. The same is true for the most characteristic clinical features of MCTD, viz. Raynaud's syndrome and polymyositis-polymyalgia. The serological and clinical symptoms mentioned are closely associated. An association between anti-Sm and the SLE symptoms butterfly erythema, nephropathia, other visceropathias and cerebrovascular disease is confirmed by the present study. Although anti-Sm has less diagnostic specificity for SLE than has anti-ds-DNA, it is useful as a diagnostic aid in SLE cases lacking the latter antibody. The results of the present study tend to support the hypothesis that anti-sRNP may be associated with a prophylactive effect against serious vasculitis and nephropathia. When anti-sRNP and anti-Sm occur together they seem to act competitively so that the symptom associated with the antibody having the highest titre tends to dominate the clinical picture. Both anti-sRNP and anti-Sm produce speckled nuclear patterns in the indirect immunofluorescence test. Sera with immunofluorescence titres below 1/25 were not found to react against either sRNP or Sm. On the other hand all sera tested that had a speckled IFL reaction 5≥1/800 also had anti-sRNP.