Immunofluorescent tracing of cytoplasmic components involved in keratinocyte differentiation.

Sera with epidermal cytoplasmic antibodies (E.C.A.) produced by human subjects after bone marrow transplantation have been studied by indirect immunofluorescen on rabbit lip sections. These sections were used in order to give on a single specimen, areas of mucosa, of parakeratotic and of orthokeratotic epithelium. It has been demonstrated that E.C.A. distinguished the basal cell layer from the upper cell layers on the three areas. Moreover, E.C.A. were not found to react identically on mucosal, parakeratotic and orthokeratotic epithelium. These findings strongly suggest that the target antigens for E.C.A. are molecules involved in keratinocyte differentiation.