An immunofluorescent and electron microscopic study of measles skin eruptions.

Immunofluorescent study was attempted to determine whether or not virus antigen were present in the epidermis of measles eruptions. The electron microscopic observations of the same materials were also performed to detect viral localization in affected skins. The failure to detect any virus antigen in affected eipdermis throughout all eruptive stages seems to be sufficient evidence to conclude that measles rash is not a manifestation of viral replication in the epidermis. Dotted fluorescences were detected in a specimen taken at pre-eruptive day in capillary endothelium of dermis. At the same stage, microtubular structures which were probably identical with measles virus nucleocapsids occurred in capillary endothelium under the electron microscopic observations. It is concluded that measles rash is possibly caused by an antigen-antibody reaction of Arthus type. On very rare occasions, measles virus nucleocaspids were found in the cytoplasm of dermal fibroblast in the vicinity of dermal capillary. Ultrastructural features of these nucleocapsids were demonstrated to be identical to features of microtubular structures found in endothelial cells.