Fluorescent antibodies in polymyositis using cultured human skin fibroblasts: granular perinuclear cytoplasmic staining pattern by sera from patients with polymyositis and pulmonary fibrosis.

Immunofluorescent antibodies were studied in sera from 48 patients with polymyositis (PM) and 149 control subjects using cultured human skin fibroblasts as substrate. Forty-six (95.8%) of PM sera showed a positive reaction. Among them, a characteristic granular perinuclear cytoplasmic staining was seen in 8 sera, including 4 with anti-Jo-1. Four of these 8 sera showed positive staining on HEp-2 cells with the same pattern. All patients showing this pattern of staining had pulmonary fibrosis which was not seen in control patients. Consequently, this staining pattern might be a specific marker for a subset of patients with PM with pulmonary fibrosis.