Absence of arylsulphatases A and B in suction blister fluid interstitial fluid and serum

Suction blisters were raised on human skin. The blister fluid was collected for enzymic assay and the epidermis over the bullae was removed before further suction of interstitial fluid. Preliminary work indicated the presence of arylsulphatases A and B in epidermis, and the same assay procedure with 4-methylumbelliferyl sulphate as substrate was used. There appeared to be no enzymatic activity in blister fluid, interstitial fluid and serum.