Mononuclear cellular infiltrates in clinically involved skin from patients with systemic sclerosis of recent onset predominantly consist of monocytes/macrophages.

Systemic sclerosis (SSc) is a generalized autoimmune disorder characterized by immunological abnormalities, microvascular dysfunction, and tissue fibrosis. This study evaluated the inflammatory processes occurring in skin of 7 patients with SSc of recent onset (average disease duration of 10 +/- 3 months) to assess the involvement of monocytes/macrophages during the early stages of SSc. All SSc skin biopsies displayed inflammatory microvascular endothelial cell activation and fibrosis. Increased numbers of infiltrating inflammatory leukocytes were present in affected skin of recent onset SSc (p < 0.01) mainly consisting of CD14-positive monocytes/macrophages (p < 0.02). CD3 T lymphocytes were only slightly elevated in SSc skin (84 +/- 39) compared to normal (51 +/- 12), but the differences were statistically not significant. The ratio of CD14/CD3 cells was substantially higher in affected skin of recent onset SSc (4.0 +/- 2.0) than in normal skin (1.4 +/- 0.5, p < 0.01). Monocytes/macrophages, therefore, are the predominant infiltrating mononuclear cell in skin lesions of recent-onset SSc. These results strongly suggest that CD14-positive monocytes/macrophages play an important role during the early stages of SSc pathogenesis.