Expression of HLA class II antigens on skin fibroblasts in scleroderma.

Skin biopsies were taken from 11 patients with morphoea, nine with acrosclerosis and 10 with diffuse systemic sclerosis and processed for immunohistochemical studies using a panel of monoclonal antibodies including antibodies to MHC class II antigens. A significantly higher percentage of HLA-DR positive dermal cells were observed in the reticular dermis in biopsies from patients with morphoea (44.1 +/- 16.2%), acrosclerosis (15.9 +/- 5.4%) and systemic sclerosis (39.5 +/- 2.3%) when compared with the controls (6.6 +/- 2%). A smaller percentage of dermal cells also expressed HLA-DP and -DQ. The degree of monocnuclear cell infiltrate in the biopsies, however, did not correlate with the percentage of HLA class II positive fibroblasts. In organ culture, the expression of the HLA class II antigens was almost totally lost after 3 days and was no longer detected on fibroblasts after 3 weeks of culture.