Immunophenotyping of chimeric cells in localized scleroderma

Localized scleroderma causes thickening of the skin due to excessive collagen deposition. This condition has clinical and histopathological similarities to chronic graft-vs-host disease. We wanted to identify whether chimeric cells are present in the affected tissue in localized scleroderma and to further investigate the role of chimerism by immunophenotyping the chimeric cells. We hypothesize that the presence of chimerism and immunotypic chimeric cells will lend to an understanding of the pathogenesis of localized scleroderma and possible mechanisms by which chimeric cells participate in autoimmunity.

We studied skin biopsies from 18 localized scleroderma patients and compared them with concurrent biopsies from unaffected skin in a subset of patients. Skin biopsies from morphoea and linear scleroderma patients were analysed for the presence of chimeric cells using male-female (X, Y) differences. Cell surface markers (CD4, CD8, CD19/20, CD68, S100, CD14 and CD56) were determined for cell phenotyping of chimeric cells.

Overall, the affected tissue contained a greater number of lymphocytic inflammatory cells. In the affected tissue, 38% of the total chimeric cells were CD68+ (dendritic cell, monocyte and macrophage marker), 29% Langerin/S100+ (dendritic cell marker), 26% CD8+ (cytotoxic T-lymphocyte marker), 20% CD19/20+ (B-lymphocyte marker), 14% CD4+ (T-helper lymphocyte) and 0% CD56+ (natural killer cell marker).

We report that not only are chimeric cells present in affected localized scleroderma lesions but they also are more likely to be dendritic cells and B lymphocytes suggesting a role in the pathogenesis of localized scleroderma.