Herbert Mescon

A chemical-histochemical evaluation of acid phosphatase activity in human skin.

Iiiethods. This is especially true in regard to the various methods for demonstration of the acid phosphataSe& ‘ ‘ 15 ‘here the specific staining is easily overshadowed l)y artefacts. In histochemical procedures, these artefacts may yield falsely positive or falsely localized stain.4 False positive reactiomis have heemi attributed to the Spontaneous hydrolysis of certain substrates amid, very rarely, to bacterial hydrolysis. False localization seemed to be due to diffusiomi of the e izyme itself as well as of its products. These products could diffuse into the mediumu or through the tissues to regions of affinity (such as the nuclei have for lead, whemi Gomori’s method for acid phosphatase is used2 ‘ ‘ ‘ 12 , 13). For these enzymes, a better qualitative evaluatiomi has been sought with the use of azo dyes. The azo-coupling reactions’ ‘ ‘ ‘ ‘ are, however, dependemit on various factors5 ‘ . These include the type of coupling of aromatic amities and hydroxy compounds, the diazonium salt chosen and the pH of the substrate. Diffusion, using the azo dye methods, may still occur’5. In a study of the sites of acid phosphatase activity in normal human skin, using Gomori’s6, Burtoii’s’, and Huteiiburg’&4 techniques, we experienced considerable difficulty in deciding upon an exact end point of incubation time for demonstrating staining at all sites of enzyme activity”. When shorter times were employed, minimal staining was observed. With longer times, by all the methods employed, additional areas of stainimig were noted. An exact interpretation of the latter observatiomi as to true degree and localization of acid phosphatase activity could not be made. We therefore undertook a limited comparative histochemical and chemical study, qualitative and quantitative, to follow certain aspects of the behavior of the reaction for acid phosphatases over relatively long incubation periods.