It has been stated recently by Shelley and Arthur1-3 that there is a causal relationship between pruritus and proteolytic enzymes. Cormia et al.4 support this theory. The principal argument in its favor is the fact that certain proteolytic enzymes, when applied externally by injection, surface application, or scratch testing, are pruritogenic. While it may be true that the mechanism of pruritus is bound up in some way with enzymic action, as are so many other vital processes, it seems to us that the question as to whether the sensation of pruritus is caused by the proteolytic action of enzymes must be reexamined critically. Our experiments tend to show that pruritus can be produced by inactivated enzymes, devoid of any enzymic activity.
Methods in Scratch Tests with Various Proteolytic Enzymes
The enzymes were diluted in the buffered phosphate saline solution recommended by Arthur and