A proteaselike permeability factor in guinea pig skin: contact activation of the latent permeability factor and its nature as a prekallikrein activator.

A proteaselike permeability factor in guinea pig skin, which was fractionated in a latent form into pseudoglobulin fractions, was activated by contact with kaolin particles at neutral pH. This contact activation was not prevented by the presence of 1 M KCl but was strongly inhibited by the simultaneous presence of hexadimethrine bromide. In this activation, the latent permeability factor was first bound to kaolin; later an active form permeability factor was released from the kaolin-bound parent molecule. Prekallikrein activator activity was also generated in this supernatant from the pretreated kaolin particle in the same time course as the permeability factor generation. Moreover, since the prekallikrein activator and permeability factor were always observed at the same fractions in every purification step, with DEAE-cellulose column chromatography, Sephadex G-75 gel filtration, and isoelectric focusing, these two molecules were recognized as identical. These results indicate that the latent permeability factor in the guinea pig skin has properties similar to those of the plasma Hageman factor.