Immunopathological investigations in purpura pigmentosa chronica

We studied the cell infiltrates and antigenic characteristics of keratinocytes in biopsies from purpura pigmentosa chronica (PPC), with eleven monoclonal antibodies against several cell surface markers of effector and/or accessory cells of the immune system and compared the reactivity patterns with those in biopsies from uninvolved skin. Immunohistochemical staining revealed a predominance of activated helper T lymphocytes in the cutaneous inflammatory infiltrate. In contrast to uninvolved skin, lesional keratinocytes were found to express HLA-DR, OKM5, Leu-8 and Leu-11b (CD16) antigens in all biopsies from the involved skin. We demonstrate here for the first time the in vivo expression of several effector and/or accessory cell markers on lesional keratinocytes and infiltrate cells in PPC.