A technique for quantitating enzyme histochemistry in adjuvant arthritic joints. II. Acid phosphatase

Enzyme histochemical reactions in unfixed and undecalcified cryostat sections of mouse knee joints with special reference to arthritic lesions

The use of unfixed and undecalcified cryostat sections of mouse knee joints is described for the study of enzyme histochemical reactions. Non-inflamed knee joints and knee joints of mice with antigen induced arthritis have been used. Joints were embedded in gelatin and subsequently cut at low speed with a motor-driven cryostat fitted with a tungsten carbide knife at an obtuse angle (10 degrees). The sections were attached to transparent tape to keep the integrity of the tissue intact. The following histochemical reactions were carried out successfully: the tetrazolium salt reaction for dehydrogenase and reductase activity, the post-azo-coupling method for acid phosphatase and cathepsin B activity and the simultaneous azo-coupling method for esterase activity. In all cases the morphology and integrity of the sections were well kept and serial sections were obtained without any difficulty. Nonspecific staining of the tape did not occur. The localization of the final reaction product was meeting criteria for specific and precise histochemical methods with the exception of the metal salt method because of nonspecific staining of undecalcified bone. Cytophotometry of the final reaction product appeared to be reproducible and valid as demonstrated by reaction for glucose-6-phosphate dehydrogenase activity in synoviocytes from knee joints with induced arthritis. End point measurements as well as kinetic measurements of the formazan production were performed and linear relationships were found between the specific formazan formation and section thickness or incubation time, respectively. It is concluded that cryostat sections attached to transparent tape are an excellent tool for the study of the metabolism in tissues adjacent to bone matrix.(ABSTRACT TRUNCATED AT 250 WORDS)

Adjuvant polyarthritis in rats: is this a satisfactory model for screening anti-arthritic drugs?

The pathological and biochemical features of the polyarthritis in rats induced by Freund's adjuvant are briefly reviewed. The object of this is to highlight recent studies that provide a basis for specifically improving procedures employed in screening the activity and mode of action of anti-inflammatory/antiarthritic drugs--especially those with possible disease modifying activity. Current screening procedures involve the simple measurement of hind-paw or joint swelling. This may not reflect the extent of degradation or systemic changes in arthritis. It is suggested that it is possible to more precisely measure the extent of joint degradation by the following: (1) X-ray monitoring of joints afflicted with the disease, (2) Histological and morphological examination (the latter in alkali cleared--Alizarin stained preparations) of hindlimbs, (3) Quantitative histoenzymic and biochemical analysis of degradative enzymes and inflammatory mediators. Additional to this specific immunological and systemic (blood, liver) changes should be measured in primary screening in recognition that arthritis is a disease not only of joints but involving the immune, hepatic and possibly other organ systems and that these systemic components clearly have effects on joints. Only by a combined analysis of both local joint and systemic changes during drug treatment will it be possible to discriminate new drugs with disease-modifying activity.