The activation of antigens of the basement membrane zone by proteolytic enzymes in vitro.

Following brief exposure of cryostat sections of human skin to the action of proteolytic enzymes (papain or trypsin), there was a pronounced increase in the antibody binding sites of the basement membrane zone, shown in indirect immunofluorescence by an increased intensity in fluorescence of the basement membrane zone as compared with preparations which had not previously undergone incubation, and by an increase of 5-6 (papain) or 4-5 (trypsin) titre dilution steps. This effect was practically absent when guinea-pig tongue was used as the antigenic substrate. In conjunction with findings published in the literature, our results can be interpreted as indicating that the activation of the basement membrane zone antigens by proteolytic enzymes is associated with an increase in antigenicity which results in the formation of "auto-antibodies" of the basement membrane zone antibody type.