Cell infiltrate in progressive pigmented purpura (Schamberg's disease): Immunophenotype, adhesion receptors, and intercellular relationships

Progressive pigmented purpura (Schamberg's disease), a form of purpura pigmentosa chronica, is a lymphocytic capillaritis of unknown etiology and obscure pathogenesis. Our purpose was to assess the expression of cell membrane antigens (CD3, CD4, CD1a, CD36), of adhesion receptors (leukocyte function adhesion 1, LFA‐1, endothelial leukocyte adhesion molecule 1, ELAM‐1) intercellular adhesion molecule 1, ICAM‐1), and the intercellular relationships in the early phase of the disease. Methods. Quantitative immunohistochemistry and electron‐microscopy were performed on specimens of five subjects, aged 45 to 63 years. These studies were repeated in two patients after treatment with topical corticosteroid (betamethasone valerate cream 0.1%) and psoralen‐ultraviolet A (puva). Results. The infiltrate consisted mainly of CD4+ lymphocytes and CD1a+ dendritic cells. Electron‐microscopic investigation showed typical lymphocytes and two distinct types of dendritic cells. In the very early phase of the disease the adhesion receptors LFA‐i and ICAM‐1 were expressed intensely by all infiltrating cells; the adhesion receptors icam‐1 and ELAM‐i were expressed by endothelial cells. Close contact occured between lymphocytes and dendritic cells. After PUVA (120 J per cm2) and topical steroid therapy the infiltrate disappeared completely. Conclusions. These data suggest that a cell‐mediated immune mechanism may be important in progressive pigmented purpura and that the early endothelial expression