A histochemical method for sulfatase activity in hemic cells and organ imprints.

EUKOCYTES are convenient cells to sample for an estimate of cellular enzyme activity. The use of the white cell series for this purpose has aocordingly become of increasing clinical and research importance in hematology.1.2 Moreover, the degree of activity of an enzyme system in a leukocyte might well be representative of the relative enzyme activity in other cells which are less accessible to direct study. If this were consistently true, a screening approach using white cells would become of practical interest to many other disciplines concerned with the diagnosis and study of human enzyme errors. The biological and pathological importance of sulfated molecules is increasingly clear.3 Thus, the suiphatase enzyme systems. which help regulate the concentration of these molecules, become of general interest, as have the phosphatase systems. However, sulfatase determinations in body fluids and other loci present a number of difficult problems.6”#{176}’1’ Moreover, sulfatase enzyme activity must ultimately be localized to some cellular level. No satisfactory histochemical method for sulfatase activity in hemic cells or in organ imprints has hitherto been available.4’5 In the technic finally evolved here, the principle of measuring sulfatase activity against a naphthyl ( aryl) sulfate substrate, as described by Rutenberg et al.,4 is used. Enzymatic splitting of the sulfuric ester group has been visualized here, however, by combining the released naphthol with fast blue RB. This reaction product forms a visible brown precipitate in the cell ( fig. 1 ) . With this present method, arylsulfatase activity (ASA ) has been determined in normal human cells of peripheral blood and bone marrow. Representative species of laboratory animals have also been studied. The known vagaries of histochemical technics have made it obligatory to test the validity of this ASA method in some detail and to record the findings. In addition, certain factors influencing ASA have been noted which may be of clinical interest.