Damaging effect of peripheral mononuclear cells of dermatomyositis on cultured human skin fibroblasts.
When human skin fibroblasts were incubated with mononuclear cells (MNC) from 6 patients with dermatomyositis (DM), striking attachment of MNC around fibroblasts was observed. Simultaneously, cell number and 3H-thymidine incorporation of fibroblasts after 4 days of incubation were significantly decreased. MNC of normal subjects, of patients with systemic lupus erythematosus, myasthenia gravis, rheumatoid arthritis, and other miscellaneous diseases with skin manifestations did not show this effect. MNC of patients with DM did not adhere to KYM-1 cells (human rhabdomyosarcoma cell-line) and did not inhibit cell proliferation of these cells. Our study strongly suggests that cell mediated injury of fibroblasts might play an important role in the pathogenesis of DM.