The Uptake of Glycine-¹⁴C into the Adenine and Guanine of DNA and Insoluble RNA of Human Leucocytes

Summary

Kaplan et al. (1) have recently reported that glycine-¹⁴C uptake into the adenine and guanine of DNA and ‘insoluble’ RNA of human leucocytes was found to be significantly greater in patients with primary gout than in normal controls. These observations have been confirmed in this investigation and extended to include other subjects. It was noted that patients with asymptomatic hyperuricemia showed a normal glycine uptake in this in vitro system. On the other hand, in patients with chronic renal disease and secondary hyperuricemia, the glycine uptake was found to be enhanced, indicating that excessive purine formation may contribute to the hyperuricemia which accompanies chronic renal failure. In addition, leucocytes from normal females showed an increased glycine uptake as compared with those obtained from normal males, despite the presence of significantly lower serum uric acid levels in the female subjects. Furthermore, while a positive but insignificant correlation was observed between the glycine uptake and serum uric acid in the normal males studied (r=+0.577), the correlation was negative in the females (r=−0.585; P < 0.05). These results indicate that there may be feedback mechanisms controlling purine synthesis in females that may not be present in males. The in vitro findings in the patients with primary gout appear to parallel the observations made by earlier investigators on glycine incorporation into uric acid in the intact subject. It is suggested, therefore, that the isolated human leucocyte may serve as a useful and convenient model for studying some of the manifold aspects of purine metabolism in man. Nevertheless, additional studies will be required in order to confirm that overall changes in purine metabolism in a variety of clinical situations is accurately reflected in the simple intact cell system described in this investigation.