title: Detection of dihydroorotate dehydrogenase activity as a marker of de novo nucleic acid synthesis in germinal centers of spleens following antigen administration.
abstract: A histochemical technique, developed for the localization of DHO-D activity in tissue, has been utilized to study the distribution of this activity in rabbit spleen. This enzyme is involved in the de novo synthesis of pyrimidines of nucleic acids via orotic acid as an intermediate. The enzyme was found to be most active at the periphery of follicles in the resting spleen. Following antigenic challenge, enzyme activity became prominent for several days in macrophages within germinal centers, but not in the intensely pyroninophilic cells which are the dominant cell type of these structures. Antigenicity of the injected compound appeared to be necessary for the production of this effect. The pattern of localization of DHO-D is similar to the pattern of distribution of antigen within splenic tissue.
mesh_terms: D000818:Animals; D000941:Antigens / Q000276:immunology*; D004081:Dihydroorotate Oxidase / Q000378:metabolism*; D006651:Histocytochemistry; D006801:Humans; D008264:Macrophages / Q000201:enzymology; D009696:Nucleic Acids / Q000096:biosynthesis*; D010088:Oxidoreductases / Q000378:metabolism*; D011817:Rabbits; D013154:Spleen / Q000033:anatomy & histology / Q000201:enzymology*
chemical_list: D000941:Antigens; D009696:Nucleic Acids; D010088:Oxidoreductases; D004081:Dihydroorotate Oxidase