Introduction: Adenosine deaminase (ADA), purine nucleoside phosphorylase (PNPase), S-adenosylhomocysteine hydrolase (SAHH), 5'-nucleotidase (5N), and deoxycytidine kinase (dCK) are involved in purine salvage metabolism. Changes of the activities of the above enzymes have been observed in blood cells in patients with immunological disorders.
Materials and methods: The activities of ADA, PNPase, SAHH, 5'N, and dCK in lysates of leukocytes and erythrocytes, obtained from patients with Graves' or Hashimoto's disease, were measured, using chromatographic analysis. Serum concentrations of antithyroglobulin (Tg Ab) and antithyroperoxidase (TPO Ab) antibodies were measured by an immunoenzymatic method.
Results: (1) ADA activity in leukocytes, obtained from patients with Hashimoto's disease, was significantly higher than in control leukocytes, as well as in leukocytes from patients with Graves' disease; (2) dCK activities in leukocytes from patients with both Graves' and Hashimoto's diseases were approximately four and five times higher, respectively, than in leukocytes of control subjects; (3) a positive correlation was observed between dCK activity in leukocytes and serum Tg Ab concentration in patients with Graves' disease. In conclusion, the increased ADA and dCK activities in leukocytes from patients with Graves' and Hashimoto's diseases may be regarded as indicators of autoimmunological thyroid diseases.