Immunofluorescence studies in progressive systemic sclerosis (scleroderma) and mixed connective tissue disease

Immunofluorescence (IF) investigations of the skin were performed in thirty patients with progressive systemic sclerosis (scleroderma) and eight patients with mixed connective tissue disease (MCTD). The results show that speckled epidermal nuclear immunoglobulin deposition occurs not only in MCTD but also in true scleroderma. Granular IgM deposition at the dermo-epidermal junction of light-exposed skin was detected in both groups of patients, but six of eight MCTD patients also showed a granular IgM band in non-exposed skin. Antinuclear antibodies (ANA) were demonstrated in the sera of 96% and 100% of patients with scleroderma and MCTD respectively. The pattern of nuclear IF staining in scleroderma included dense fine speckles, large coarse speckles, threads, nucleolar and centromere staining. In MCTD, by contrast, the ANA staining pattern consisted of threads. The significance of ANA titres and immunological specificities for the in vivo reaction of serum ANA with epidermal nuclear antigens is discussed.