Background and design: The pathogenesis of scleroderma is still unknown. Recently, it has become possible to identify different subpopulations of dermal spindle-shaped cells using anti-CD34 and anti-factor XIIIa antibodies. To elucidate whether entire populations of dermal fibroblasts or only a subpopulation of cells are involved in the fibrosis of scleroderma, we compared the staining pattern of these antibodies and antiprocollagen antibody in paraffin-embedded skin sections from the lesions of 27 patients with scleroderma and 15 patients with other collagen diseases and from normal skin of 17 subjects. Cryostat sections from both involved and uninvolved skin of four patients with scleroderma were also stained with anti-CD34, anti-factor XIIIa, and anti-proline-4-hydroxylase antibodies.
Results: CD34+ cells were few or absent in the lesions of scleroderma, while a number of CD34+ cells were found in the lesions of other collagen diseases and in normal skin. In contrast, large numbers of factor XIIIa-and procollagen-positive cells were noted in the lesions of scleroderma. Even in the study in which cryostat sections were used, CD34+ cells were totally absent from the lesions of scleroderma, while there were numerous proline-4-hydroxylase-positive cells. Furthermore, although detectable in the clinically uninvolved skin of these patients, CD34+ cells were less frequent and more slender than those in normal skin.
Conclusion: Immunohistologic staining with anti-CD34 and other antibodies to dermal spindle-shaped cells demonstrated a selective disappearance of CD34+ spindle-shaped cells from the lesions of scleroderma. It suggests that CD34+ cells might be important target cells in the autoreactive phenomenon in scleroderma.