The binding of epidermolytic toxin from Staphylococcus aureus to mouse epidermal tissue.

Fluorescein-labelled epidermolytic toxin (FTC-toxin) of Staphylococcus aureus and ferritin-toxin conjugate have been prepared and purified. FTC-toxin bound selectively to cryostat and resin-impregnated sections of neonatal mouse skin. Binding was localized at the keratohyalin granules and in the stratum corneum. In an epidermal cell (granular, spinous and basal) preparation, only keratohyalin granules of the granular cells bound FTC-toxin. Ferritin-toxin conjugate bound to skin sections at the same two sites as FTC-toxin and was competitive with the binding of free toxin. Keratohyalin granules in unstained sections had a novel 'patched' appearance under the electron microscope, and the ferritin-toxin conjugate bound preferentially to the electron-lucent areas. In the stratum corneum it was shown by quantitative estimation that the target density decreased as the surface of the tissue was approached.